diff --git a/Jakefile.js b/Jakefile.js
index 9ac41556d9..d447ac660e 100644
--- a/Jakefile.js
+++ b/Jakefile.js
@@ -507,7 +507,7 @@ function cleanTestDirs() {
 // used to pass data from jake command line directly to run.js
 function writeTestConfigFile(tests, testConfigFile) {
     console.log('Running test(s): ' + tests);
-    var testConfigContents = '{\n' + '\ttest: [\'' + tests + '\']\n}';
+    var testConfigContents = JSON.stringify({ test: [tests]});
     fs.writeFileSync('test.config', testConfigContents);
 }
 
@@ -690,4 +690,4 @@ task('tsc-instrumented', [loggedIOJsPath, instrumenterJsPath, tscFile], function
         complete();
     });
     ex.run();
-}, { async: true });
+}, { async: true });
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 28242aba01..2c445fe116 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -11368,6 +11368,10 @@ module ts {
         function checkSourceFileWorker(node: SourceFile) {
             let links = getNodeLinks(node);
             if (!(links.flags & NodeCheckFlags.TypeChecked)) {
+                if (node.isDefaultLib && compilerOptions.skipDefaultLibCheck) {
+                    return;
+                }
+
                 // Grammar checking
                 checkGrammarSourceFile(node);
 
diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 61739fceca..a3065bd7a4 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -103,6 +103,10 @@ module ts {
             name: "noResolve",
             type: "boolean",
         },
+        {
+            name: "skipDefaultLibCheck",
+            type: "boolean",
+        },
         {
             name: "out",
             type: "string",
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index ed9647970c..dde1e3d6b5 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -21,7 +21,7 @@ module ts {
             get,
             set,
             contains,
-            delete: deleteItem,
+            remove,
             forEachValue: forEachValueInMap
         }
 
@@ -37,7 +37,7 @@ module ts {
             return hasProperty(files, normalizeKey(fileName));
         }
 
-        function deleteItem (fileName: string) {
+        function remove (fileName: string) {
             let key = normalizeKey(fileName);
             delete files[key];
         }
diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
index 2249ca5e88..ddccfad310 100644
--- a/src/compiler/emitter.ts
+++ b/src/compiler/emitter.ts
@@ -4503,7 +4503,7 @@ var __param = (this && this.__param) || function (paramIndex, decorator) {
                         emitDeclarationName(node);
                         write(`", `);
                         emitDeclarationName(node);
-                        write(")");
+                        write(");");
                     }
                     emitExportMemberAssignments(node.name);
                 }
@@ -4624,7 +4624,7 @@ var __param = (this && this.__param) || function (paramIndex, decorator) {
                         emitDeclarationName(node);
                         write(`", `);
                         emitDeclarationName(node);
-                        write(")");
+                        write(");");
                     }
                     emitExportMemberAssignments(<Identifier>node.name);
                 }
diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 8938981996..671420468b 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -144,7 +144,7 @@ module ts {
         let program: Program;
         let files: SourceFile[] = [];
         let diagnostics = createDiagnosticCollection();
-        let seenNoDefaultLib = options.noLib;
+        let skipDefaultLib = options.noLib;
         let commonSourceDirectory: string;
         let diagnosticsProducingTypeChecker: TypeChecker;
         let noDiagnosticsTypeChecker: TypeChecker;
@@ -154,9 +154,9 @@ module ts {
         host = host || createCompilerHost(options);
         let filesByName = createFileMap<SourceFile>(host.getCanonicalFileName);
 
-        forEach(rootNames, name => processRootFile(name, false));
-        if (!seenNoDefaultLib) {
-            processRootFile(host.getDefaultLibFileName(options), true);
+        forEach(rootNames, name => processRootFile(name, /*isDefaultLib:*/ false));
+        if (!skipDefaultLib) {
+            processRootFile(host.getDefaultLibFileName(options), /*isDefaultLib:*/ true);
         }
         verifyCompilerOptions();
 
@@ -382,7 +382,7 @@ module ts {
                 });
                 filesByName.set(canonicalName, file);
                 if (file) {
-                    seenNoDefaultLib = seenNoDefaultLib || file.hasNoDefaultLib;
+                    skipDefaultLib = skipDefaultLib || file.hasNoDefaultLib;
 
                     // Set the source file for normalized absolute path
                     filesByName.set(canonicalAbsolutePath, file);
@@ -393,6 +393,7 @@ module ts {
                         processImportedModules(file, basePath);
                     }
                     if (isDefaultLib) {
+                        file.isDefaultLib = true;
                         files.unshift(file);
                     }
                     else {
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index d9a7262f2e..f496b88069 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -7,7 +7,7 @@ module ts {
         get(fileName: string): T;
         set(fileName: string, value: T): void;
         contains(fileName: string): boolean;
-        delete(fileName: string): void;
+        remove(fileName: string): void;
         forEachValue(f: (v: T) => void): void;
     }
 
@@ -1151,7 +1151,8 @@ module ts {
 
         // The first node that causes this file to be an external module
         /* @internal */ externalModuleIndicator: Node;
-        
+
+        /* @internal */ isDefaultLib: boolean;
         /* @internal */ identifiers: Map<string>;
         /* @internal */ nodeCount: number;
         /* @internal */ identifierCount: number;
@@ -1832,6 +1833,7 @@ module ts {
         experimentalDecorators?: boolean;
         emitDecoratorMetadata?: boolean;
         /* @internal */ stripInternal?: boolean;
+        /* @internal */ skipDefaultLibCheck?: boolean;
         [option: string]: string | number | boolean;
     }
 
diff --git a/src/harness/harness.ts b/src/harness/harness.ts
index 86cc255b06..82afea4cf4 100644
--- a/src/harness/harness.ts
+++ b/src/harness/harness.ts
@@ -808,9 +808,15 @@ module Harness {
             }
         }
 
-        export function createSourceFileAndAssertInvariants(fileName: string, sourceText: string, languageVersion: ts.ScriptTarget, assertInvariants = true) {
+        export function createSourceFileAndAssertInvariants(
+            fileName: string,
+            sourceText: string,
+            languageVersion: ts.ScriptTarget,
+            assertInvariants: boolean) {
+
             // Only set the parent nodes if we're asserting invariants.  We don't need them otherwise.
             var result = ts.createSourceFile(fileName, sourceText, languageVersion, /*setParentNodes:*/ assertInvariants);
+
             if (assertInvariants) {
                 Utils.assertInvariants(result, /*parent:*/ undefined);
             }
@@ -821,8 +827,8 @@ module Harness {
         const lineFeed = "\n";
 
         export var defaultLibFileName = 'lib.d.ts';
-        export var defaultLibSourceFile = createSourceFileAndAssertInvariants(defaultLibFileName, IO.readFile(libFolder + 'lib.core.d.ts'), /*languageVersion*/ ts.ScriptTarget.Latest);
-        export var defaultES6LibSourceFile = createSourceFileAndAssertInvariants(defaultLibFileName, IO.readFile(libFolder + 'lib.core.es6.d.ts'), /*languageVersion*/ ts.ScriptTarget.Latest);
+        export var defaultLibSourceFile = createSourceFileAndAssertInvariants(defaultLibFileName, IO.readFile(libFolder + 'lib.core.d.ts'), /*languageVersion*/ ts.ScriptTarget.Latest, /*assertInvariants:*/ true);
+        export var defaultES6LibSourceFile = createSourceFileAndAssertInvariants(defaultLibFileName, IO.readFile(libFolder + 'lib.core.es6.d.ts'), /*languageVersion*/ ts.ScriptTarget.Latest, /*assertInvariants:*/ true);
 
         // Cache these between executions so we don't have to re-parse them for every test
         export var fourslashFileName = 'fourslash.ts';
@@ -832,13 +838,14 @@ module Harness {
             return ts.sys.useCaseSensitiveFileNames ? fileName : fileName.toLowerCase();
         }
 
-        export function createCompilerHost(inputFiles: { unitName: string; content: string; }[],
-            writeFile: (fn: string, contents: string, writeByteOrderMark: boolean) => void,
-            scriptTarget: ts.ScriptTarget,
-            useCaseSensitiveFileNames: boolean,
-            // the currentDirectory is needed for rwcRunner to passed in specified current directory to compiler host
-            currentDirectory?: string,
-            newLineKind?: ts.NewLineKind): ts.CompilerHost {
+        export function createCompilerHost(
+                inputFiles: { unitName: string; content: string; }[],
+                writeFile: (fn: string, contents: string, writeByteOrderMark: boolean) => void,
+                scriptTarget: ts.ScriptTarget,
+                useCaseSensitiveFileNames: boolean,
+                // the currentDirectory is needed for rwcRunner to passed in specified current directory to compiler host
+                currentDirectory?: string,
+                newLineKind?: ts.NewLineKind): ts.CompilerHost {
 
             // Local get canonical file name function, that depends on passed in parameter for useCaseSensitiveFileNames
             function getCanonicalFileName(fileName: string): string {
@@ -852,7 +859,7 @@ module Harness {
             function register(file: { unitName: string; content: string; }) {
                 if (file.content !== undefined) {
                     var fileName = ts.normalizePath(file.unitName);
-                    filemap[getCanonicalFileName(fileName)] = createSourceFileAndAssertInvariants(fileName, file.content, scriptTarget);
+                    filemap[getCanonicalFileName(fileName)] = createSourceFileAndAssertInvariants(fileName, file.content, scriptTarget, /*assertInvariants:*/ true);
                 }
             };
             inputFiles.forEach(register);
@@ -875,7 +882,7 @@ module Harness {
                     }
                     else if (fn === fourslashFileName) {
                         var tsFn = 'tests/cases/fourslash/' + fourslashFileName;
-                        fourslashSourceFile = fourslashSourceFile || createSourceFileAndAssertInvariants(tsFn, Harness.IO.readFile(tsFn), scriptTarget);
+                        fourslashSourceFile = fourslashSourceFile || createSourceFileAndAssertInvariants(tsFn, Harness.IO.readFile(tsFn), scriptTarget, /*assertInvariants:*/ true);
                         return fourslashSourceFile;
                     }
                     else {
@@ -964,7 +971,8 @@ module Harness {
                     settingsCallback(null);
                 }
 
-                var newLine = '\r\n';
+                let newLine = '\r\n';
+                options.skipDefaultLibCheck = true;
 
                 // Files from built\local that are requested by test "@includeBuiltFiles" to be in the context.
                 // Treat them as library files, so include them in build, but not in baselines.
@@ -1050,6 +1058,10 @@ module Harness {
                             options.outDir = setting.value;
                             break;
 
+                        case 'skipdefaultlibcheck':
+                            options.skipDefaultLibCheck = setting.value === "true";
+                            break;
+
                         case 'sourceroot':
                             options.sourceRoot = setting.value;
                             break;
@@ -1134,9 +1146,11 @@ module Harness {
                 var fileOutputs: GeneratedFile[] = [];
                 
                 var programFiles = inputFiles.concat(includeBuiltFiles).map(file => file.unitName);
-                var program = ts.createProgram(programFiles, options, createCompilerHost(inputFiles.concat(includeBuiltFiles).concat(otherFiles),
+                var compilerHost = createCompilerHost(
+                    inputFiles.concat(includeBuiltFiles).concat(otherFiles),
                     (fn, contents, writeByteOrderMark) => fileOutputs.push({ fileName: fn, code: contents, writeByteOrderMark: writeByteOrderMark }),
-                    options.target, useCaseSensitiveFileNames, currentDirectory, options.newLine));
+                    options.target, useCaseSensitiveFileNames, currentDirectory, options.newLine);
+                var program = ts.createProgram(programFiles, options, compilerHost);
 
                 var emitResult = program.emit();
 
@@ -1480,7 +1494,8 @@ module Harness {
             "errortruncation", "usecasesensitivefilenames", "preserveconstenums",
             "includebuiltfile", "suppressimplicitanyindexerrors", "stripinternal",
             "isolatedmodules", "inlinesourcemap", "maproot", "sourceroot",
-            "inlinesources", "emitdecoratormetadata", "experimentaldecorators"];
+            "inlinesources", "emitdecoratormetadata", "experimentaldecorators",
+            "skipdefaultlibcheck"];
 
         function extractCompilerSettings(content: string): CompilerSetting[] {
 
diff --git a/src/harness/projectsRunner.ts b/src/harness/projectsRunner.ts
index 324524272e..cb454c00e6 100644
--- a/src/harness/projectsRunner.ts
+++ b/src/harness/projectsRunner.ts
@@ -174,7 +174,7 @@ class ProjectRunner extends RunnerBase {
                 else {
                     var text = getSourceFileText(fileName);
                     if (text !== undefined) {
-                        sourceFile = Harness.Compiler.createSourceFileAndAssertInvariants(fileName, text, languageVersion);
+                        sourceFile = Harness.Compiler.createSourceFileAndAssertInvariants(fileName, text, languageVersion, /*assertInvariants:*/ true);
                     }
                 }
 
diff --git a/src/harness/runner.ts b/src/harness/runner.ts
index 37451639d7..eae4d77bb2 100644
--- a/src/harness/runner.ts
+++ b/src/harness/runner.ts
@@ -38,41 +38,45 @@ var testConfigFile =
     (Harness.IO.fileExists(testconfig) ? Harness.IO.readFile(testconfig) : '');
 
 if (testConfigFile !== '') {
-    // TODO: not sure why this is crashing mocha
-    //var testConfig = JSON.parse(testConfigRaw);
-    var testConfig = testConfigFile.match(/test:\s\['(.*)'\]/);
-    var options = testConfig ? [testConfig[1]] : [];
-    for (var i = 0; i < options.length; i++) {
-        switch (options[i]) {
-            case 'compiler':
-                runners.push(new CompilerBaselineRunner(CompilerTestType.Conformance));
-                runners.push(new CompilerBaselineRunner(CompilerTestType.Regressions));
-                runners.push(new ProjectRunner());  
-                break;
-            case 'conformance':
-                runners.push(new CompilerBaselineRunner(CompilerTestType.Conformance));
-                break;
-            case 'project':
-                runners.push(new ProjectRunner());
-                break;
-            case 'fourslash':
-                runners.push(new FourSlashRunner(FourSlashTestType.Native));
-                break;
-            case 'fourslash-shims':
-                runners.push(new FourSlashRunner(FourSlashTestType.Shims));
-                break;
-            case 'fourslash-server':
-                runners.push(new FourSlashRunner(FourSlashTestType.Server));
-                break;
-            case 'fourslash-generated':
-                runners.push(new GeneratedFourslashRunner(FourSlashTestType.Native));
-                break;
-            case 'rwc':
-                runners.push(new RWCRunner());
-                break;
-            case 'test262':
-                runners.push(new Test262BaselineRunner());
-                break;
+    var testConfig = JSON.parse(testConfigFile);
+
+    if (testConfig.test && testConfig.test.length > 0) {
+        for (let option of testConfig.test) {
+            if (!option) {
+                continue;
+            }
+            ts.sys.write("Option: " + option + "\r\n");
+            switch (option) {
+                case 'compiler':
+                    runners.push(new CompilerBaselineRunner(CompilerTestType.Conformance));
+                    runners.push(new CompilerBaselineRunner(CompilerTestType.Regressions));
+                    runners.push(new ProjectRunner());
+                    break;
+                case 'conformance':
+                    runners.push(new CompilerBaselineRunner(CompilerTestType.Conformance));
+                    break;
+                case 'project':
+                    runners.push(new ProjectRunner());
+                    break;
+                case 'fourslash':
+                    runners.push(new FourSlashRunner(FourSlashTestType.Native));
+                    break;
+                case 'fourslash-shims':
+                    runners.push(new FourSlashRunner(FourSlashTestType.Shims));
+                    break;
+                case 'fourslash-server':
+                    runners.push(new FourSlashRunner(FourSlashTestType.Server));
+                    break;
+                case 'fourslash-generated':
+                    runners.push(new GeneratedFourslashRunner(FourSlashTestType.Native));
+                    break;
+                case 'rwc':
+                    runners.push(new RWCRunner());
+                    break;
+                case 'test262':
+                    runners.push(new Test262BaselineRunner());
+                    break;
+            }
         }
     }
 }
diff --git a/src/services/services.ts b/src/services/services.ts
index 79de1821aa..5f030bf320 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -743,6 +743,7 @@ module ts {
         public parseDiagnostics: Diagnostic[];
         public bindDiagnostics: Diagnostic[];
 
+        public isDefaultLib: boolean;
         public hasNoDefaultLib: boolean;
         public externalModuleIndicator: Node; // The first node that causes this file to be an external module
         public nodeCount: number;
@@ -1993,7 +1994,7 @@ module ts {
 
             Debug.assert(entry.languageServiceRefCount >= 0);
             if (entry.languageServiceRefCount === 0) {
-                bucket.delete(fileName);
+                bucket.remove(fileName);
             }
         }
 
diff --git a/tests/baselines/reference/TypeGuardWithEnumUnion.types b/tests/baselines/reference/TypeGuardWithEnumUnion.types
index 16d999e46f..61cce562ba 100644
--- a/tests/baselines/reference/TypeGuardWithEnumUnion.types
+++ b/tests/baselines/reference/TypeGuardWithEnumUnion.types
@@ -35,14 +35,14 @@ function f1(x: Color | string) {
 }
 
 function f2(x: Color | string | string[]) {
->f2 : (x: string | string[] | Color) => void
->x : string | string[] | Color
+>f2 : (x: string | Color | string[]) => void
+>x : string | Color | string[]
 >Color : Color
 
     if (typeof x === "object") {
 >typeof x === "object" : boolean
 >typeof x : string
->x : string | string[] | Color
+>x : string | Color | string[]
 >"object" : string
 
         var y = x;
@@ -55,7 +55,7 @@ function f2(x: Color | string | string[]) {
     if (typeof x === "number") {
 >typeof x === "number" : boolean
 >typeof x : string
->x : string | string[] | Color
+>x : string | Color | string[]
 >"number" : string
 
         var z = x;
@@ -77,7 +77,7 @@ function f2(x: Color | string | string[]) {
     if (typeof x === "string") {
 >typeof x === "string" : boolean
 >typeof x : string
->x : string | string[] | Color
+>x : string | Color | string[]
 >"string" : string
 
         var a = x;
@@ -89,11 +89,11 @@ function f2(x: Color | string | string[]) {
     }
     else {
         var b = x;
->b : string[] | Color
->x : string[] | Color
+>b : Color | string[]
+>x : Color | string[]
 
         var b: Color | string[];
->b : string[] | Color
+>b : Color | string[]
 >Color : Color
     }
 }
diff --git a/tests/baselines/reference/arrayLiterals.types b/tests/baselines/reference/arrayLiterals.types
index 841de33696..e103241dd0 100644
--- a/tests/baselines/reference/arrayLiterals.types
+++ b/tests/baselines/reference/arrayLiterals.types
@@ -2,8 +2,8 @@
 // Empty array literal with no contextual type has type Undefined[]
 
 var arr1= [[], [1], ['']];
->arr1 : (string[] | number[])[]
->[[], [1], ['']] : (string[] | number[])[]
+>arr1 : (number[] | string[])[]
+>[[], [1], ['']] : (number[] | string[])[]
 >[] : undefined[]
 >[1] : number[]
 >1 : number
@@ -11,8 +11,8 @@ var arr1= [[], [1], ['']];
 >'' : string
 
 var arr2 = [[null], [1], ['']];
->arr2 : (string[] | number[])[]
->[[null], [1], ['']] : (string[] | number[])[]
+>arr2 : (number[] | string[])[]
+>[[null], [1], ['']] : (number[] | string[])[]
 >[null] : null[]
 >null : null
 >[1] : number[]
diff --git a/tests/baselines/reference/arrayLiterals3.errors.txt b/tests/baselines/reference/arrayLiterals3.errors.txt
index 74cfdb165d..36714162de 100644
--- a/tests/baselines/reference/arrayLiterals3.errors.txt
+++ b/tests/baselines/reference/arrayLiterals3.errors.txt
@@ -8,8 +8,8 @@ tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(17,5): error
     Type '() => string | number | boolean' is not assignable to type '() => number'.
       Type 'string | number | boolean' is not assignable to type 'number'.
         Type 'string' is not assignable to type 'number'.
-tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(32,5): error TS2322: Type '(string[] | number[])[]' is not assignable to type 'tup'.
-  Property '0' is missing in type '(string[] | number[])[]'.
+tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(32,5): error TS2322: Type '(number[] | string[])[]' is not assignable to type 'tup'.
+  Property '0' is missing in type '(number[] | string[])[]'.
 tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(33,5): error TS2322: Type 'number[]' is not assignable to type '[number, number, number]'.
   Property '0' is missing in type 'number[]'.
 tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(34,5): error TS2322: Type '(string | number)[]' is not assignable to type 'myArray'.
@@ -68,8 +68,8 @@ tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(34,5): error
     interface myArray2 extends Array<Number|String> { }
     var c0: tup = [...temp2];                         // Error
         ~~
-!!! error TS2322: Type '(string[] | number[])[]' is not assignable to type 'tup'.
-!!! error TS2322:   Property '0' is missing in type '(string[] | number[])[]'.
+!!! error TS2322: Type '(number[] | string[])[]' is not assignable to type 'tup'.
+!!! error TS2322:   Property '0' is missing in type '(number[] | string[])[]'.
     var c1: [number, number, number] = [...temp1];    // Error cannot assign number[] to [number, number, number]
         ~~
 !!! error TS2322: Type 'number[]' is not assignable to type '[number, number, number]'.
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType6_ES5.types b/tests/baselines/reference/computedPropertyNamesContextualType6_ES5.types
index 52ff0c1001..d6c97b5db8 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType6_ES5.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType6_ES5.types
@@ -17,9 +17,9 @@ declare function foo<T>(obj: I<T>): T
 >T : T
 
 foo({
->foo({    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]}) : string | number | boolean | number[] | (() => void)
+>foo({    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]}) : string | number | boolean | (() => void) | number[]
 >foo : <T>(obj: I<T>) => T
->{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: string]: string | number | boolean | number[] | (() => void); 0: () => void; p: string; }
+>{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: string]: string | number | boolean | (() => void) | number[]; 0: () => void; p: string; }
 
     p: "",
 >p : string
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType6_ES6.types b/tests/baselines/reference/computedPropertyNamesContextualType6_ES6.types
index 6998c9523c..72a1d5ba04 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType6_ES6.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType6_ES6.types
@@ -17,9 +17,9 @@ declare function foo<T>(obj: I<T>): T
 >T : T
 
 foo({
->foo({    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]}) : string | number | boolean | number[] | (() => void)
+>foo({    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]}) : string | number | boolean | (() => void) | number[]
 >foo : <T>(obj: I<T>) => T
->{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: string]: string | number | boolean | number[] | (() => void); 0: () => void; p: string; }
+>{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: string]: string | number | boolean | (() => void) | number[]; 0: () => void; p: string; }
 
     p: "",
 >p : string
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType7_ES5.types b/tests/baselines/reference/computedPropertyNamesContextualType7_ES5.types
index 1845d14596..5674f6aa39 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType7_ES5.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType7_ES5.types
@@ -17,9 +17,9 @@ declare function foo<T>(obj: I<T>): T
 >T : T
 
 foo({
->foo({    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]}) : number | number[] | (() => void)
+>foo({    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]}) : number | (() => void) | number[]
 >foo : <T>(obj: I<T>) => T
->{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: number]: number | number[] | (() => void); 0: () => void; p: string; }
+>{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: number]: number | (() => void) | number[]; 0: () => void; p: string; }
 
     p: "",
 >p : string
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType7_ES6.types b/tests/baselines/reference/computedPropertyNamesContextualType7_ES6.types
index 54d2afe4f6..93558c075e 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType7_ES6.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType7_ES6.types
@@ -17,9 +17,9 @@ declare function foo<T>(obj: I<T>): T
 >T : T
 
 foo({
->foo({    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]}) : number | number[] | (() => void)
+>foo({    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]}) : number | (() => void) | number[]
 >foo : <T>(obj: I<T>) => T
->{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: number]: number | number[] | (() => void); 0: () => void; p: string; }
+>{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: number]: number | (() => void) | number[]; 0: () => void; p: string; }
 
     p: "",
 >p : string
diff --git a/tests/baselines/reference/contextualSignatureInstantiation.types b/tests/baselines/reference/contextualSignatureInstantiation.types
index e7be6da51c..49d6871804 100644
--- a/tests/baselines/reference/contextualSignatureInstantiation.types
+++ b/tests/baselines/reference/contextualSignatureInstantiation.types
@@ -120,35 +120,35 @@ var b = baz(b, b, g);      // Should be number | string
 >g : <T>(x: T, y: T) => T
 
 var d: number[] | string[];
->d : string[] | number[]
+>d : number[] | string[]
 
 var d = foo(h);            // Should be number[] | string[]
->d : string[] | number[]
->foo(h) : string[] | number[]
+>d : number[] | string[]
+>foo(h) : number[] | string[]
 >foo : <T>(cb: (x: number, y: string) => T) => T
 >h : <T, U>(x: T, y: U) => T[] | U[]
 
 var d = bar(1, "one", h);  // Should be number[] | string[]
->d : string[] | number[]
->bar(1, "one", h) : string[] | number[]
+>d : number[] | string[]
+>bar(1, "one", h) : number[] | string[]
 >bar : <T, U, V>(x: T, y: U, cb: (x: T, y: U) => V) => V
 >1 : number
 >"one" : string
 >h : <T, U>(x: T, y: U) => T[] | U[]
 
 var d = bar("one", 1, h);  // Should be number[] | string[]
->d : string[] | number[]
->bar("one", 1, h) : string[] | number[]
+>d : number[] | string[]
+>bar("one", 1, h) : number[] | string[]
 >bar : <T, U, V>(x: T, y: U, cb: (x: T, y: U) => V) => V
 >"one" : string
 >1 : number
 >h : <T, U>(x: T, y: U) => T[] | U[]
 
 var d = baz(d, d, g);      // Should be number[] | string[]
->d : string[] | number[]
->baz(d, d, g) : string[] | number[]
+>d : number[] | string[]
+>baz(d, d, g) : number[] | string[]
 >baz : <T, U>(x: T, y: T, cb: (x: T, y: T) => U) => U
->d : string[] | number[]
->d : string[] | number[]
+>d : number[] | string[]
+>d : number[] | string[]
 >g : <T>(x: T, y: T) => T
 
diff --git a/tests/baselines/reference/destructuringParameterDeclaration3ES5.types b/tests/baselines/reference/destructuringParameterDeclaration3ES5.types
index 64bede3e2d..d51a0e32dc 100644
--- a/tests/baselines/reference/destructuringParameterDeclaration3ES5.types
+++ b/tests/baselines/reference/destructuringParameterDeclaration3ES5.types
@@ -12,7 +12,7 @@ type arrayString = Array<String>
 >String : String
 
 type someArray = Array<String> | number[];
->someArray : number[] | String[]
+>someArray : String[] | number[]
 >Array : T[]
 >String : String
 
diff --git a/tests/baselines/reference/destructuringParameterDeclaration3ES6.types b/tests/baselines/reference/destructuringParameterDeclaration3ES6.types
index aea7b2ae15..63d5d074a8 100644
--- a/tests/baselines/reference/destructuringParameterDeclaration3ES6.types
+++ b/tests/baselines/reference/destructuringParameterDeclaration3ES6.types
@@ -12,7 +12,7 @@ type arrayString = Array<String>
 >String : String
 
 type someArray = Array<String> | number[];
->someArray : number[] | String[]
+>someArray : String[] | number[]
 >Array : T[]
 >String : String
 
diff --git a/tests/baselines/reference/heterogeneousArrayLiterals.types b/tests/baselines/reference/heterogeneousArrayLiterals.types
index 81fa915ab0..ecfbf75e86 100644
--- a/tests/baselines/reference/heterogeneousArrayLiterals.types
+++ b/tests/baselines/reference/heterogeneousArrayLiterals.types
@@ -40,8 +40,8 @@ var f = [[], [1]]; // number[][]
 >1 : number
 
 var g = [[1], ['']]; // {}[]
->g : (string[] | number[])[]
->[[1], ['']] : (string[] | number[])[]
+>g : (number[] | string[])[]
+>[[1], ['']] : (number[] | string[])[]
 >[1] : number[]
 >1 : number
 >[''] : string[]
diff --git a/tests/baselines/reference/logicalOrOperatorWithEveryType.types b/tests/baselines/reference/logicalOrOperatorWithEveryType.types
index c98966acb9..ecf6b23e72 100644
--- a/tests/baselines/reference/logicalOrOperatorWithEveryType.types
+++ b/tests/baselines/reference/logicalOrOperatorWithEveryType.types
@@ -379,8 +379,8 @@ var rg7 = a7 || a6;         // object    || enum is object | enum
 >a6 : E
 
 var rg8 = a8 || a6;         // array     || enum is array | enum
->rg8 : string[] | E
->a8 || a6 : string[] | E
+>rg8 : E | string[]
+>a8 || a6 : E | string[]
 >a8 : string[]
 >a6 : E
 
@@ -439,8 +439,8 @@ var rh7 = a7 || a7;         // object    || object is object
 >a7 : { a: string; }
 
 var rh8 = a8 || a7;         // array     || object is array | object
->rh8 : string[] | { a: string; }
->a8 || a7 : string[] | { a: string; }
+>rh8 : { a: string; } | string[]
+>a8 || a7 : { a: string; } | string[]
 >a8 : string[]
 >a7 : { a: string; }
 
@@ -487,14 +487,14 @@ var ri5 = a5 || a8;         // void      || array is void | array
 >a8 : string[]
 
 var ri6 = a6 || a8;         // enum      || array is enum | array
->ri6 : string[] | E
->a6 || a8 : string[] | E
+>ri6 : E | string[]
+>a6 || a8 : E | string[]
 >a6 : E
 >a8 : string[]
 
 var ri7 = a7 || a8;         // object    || array is object | array
->ri7 : string[] | { a: string; }
->a7 || a8 : string[] | { a: string; }
+>ri7 : { a: string; } | string[]
+>a7 || a8 : { a: string; } | string[]
 >a7 : { a: string; }
 >a8 : string[]
 
diff --git a/tests/baselines/reference/systemModule7.js b/tests/baselines/reference/systemModule7.js
index 85dd42da87..0c396ddbe5 100644
--- a/tests/baselines/reference/systemModule7.js
+++ b/tests/baselines/reference/systemModule7.js
@@ -20,7 +20,7 @@ System.register([], function(exports_1) {
             (function (M) {
                 var x = 1;
             })(M = M || (M = {}));
-            exports_1("M", M)
+            exports_1("M", M);
         }
     }
 });
diff --git a/tests/baselines/reference/systemModuleDeclarationMerging.js b/tests/baselines/reference/systemModuleDeclarationMerging.js
index b745ed0489..06577c401a 100644
--- a/tests/baselines/reference/systemModuleDeclarationMerging.js
+++ b/tests/baselines/reference/systemModuleDeclarationMerging.js
@@ -20,7 +20,7 @@ System.register([], function(exports_1) {
             (function (F) {
                 var x;
             })(F = F || (F = {}));
-            exports_1("F", F)
+            exports_1("F", F);
             C = (function () {
                 function C() {
                 }
@@ -30,14 +30,14 @@ System.register([], function(exports_1) {
             (function (C) {
                 var x;
             })(C = C || (C = {}));
-            exports_1("C", C)
+            exports_1("C", C);
             (function (E) {
             })(E || (E = {}));
-            exports_1("E", E)
+            exports_1("E", E);
             (function (E) {
                 var x;
             })(E = E || (E = {}));
-            exports_1("E", E)
+            exports_1("E", E);
         }
     }
 });
diff --git a/tests/baselines/reference/systemModuleNonTopLevelModuleMembers.js b/tests/baselines/reference/systemModuleNonTopLevelModuleMembers.js
index 87e96259bf..39a957ed69 100644
--- a/tests/baselines/reference/systemModuleNonTopLevelModuleMembers.js
+++ b/tests/baselines/reference/systemModuleNonTopLevelModuleMembers.js
@@ -29,11 +29,11 @@ System.register([], function(exports_1) {
             (function (TopLevelModule) {
                 var v;
             })(TopLevelModule = TopLevelModule || (TopLevelModule = {}));
-            exports_1("TopLevelModule", TopLevelModule)
+            exports_1("TopLevelModule", TopLevelModule);
             (function (TopLevelEnum) {
                 TopLevelEnum[TopLevelEnum["E"] = 0] = "E";
             })(TopLevelEnum || (TopLevelEnum = {}));
-            exports_1("TopLevelEnum", TopLevelEnum)
+            exports_1("TopLevelEnum", TopLevelEnum);
             (function (TopLevelModule2) {
                 var NonTopLevelClass = (function () {
                     function NonTopLevelClass() {
@@ -52,7 +52,7 @@ System.register([], function(exports_1) {
                 })(TopLevelModule2.NonTopLevelEnum || (TopLevelModule2.NonTopLevelEnum = {}));
                 var NonTopLevelEnum = TopLevelModule2.NonTopLevelEnum;
             })(TopLevelModule2 = TopLevelModule2 || (TopLevelModule2 = {}));
-            exports_1("TopLevelModule2", TopLevelModule2)
+            exports_1("TopLevelModule2", TopLevelModule2);
         }
     }
 });
diff --git a/tests/baselines/reference/typeGuardsInConditionalExpression.types b/tests/baselines/reference/typeGuardsInConditionalExpression.types
index dffcca7e2b..3965abfe96 100644
--- a/tests/baselines/reference/typeGuardsInConditionalExpression.types
+++ b/tests/baselines/reference/typeGuardsInConditionalExpression.types
@@ -363,9 +363,9 @@ function foo12(x: number | string | boolean) {
 >10 : number
 >x.toString().length : number
 >x.toString() : string
->x.toString : () => string
+>x.toString : (radix?: number) => string
 >x : string | number | boolean
->toString : () => string
+>toString : (radix?: number) => string
 >length : number
 
         : ((b = x) // x is number | boolean | string  - changed in true branch
diff --git a/tests/cases/conformance/parser/ecmascript5/StrictMode/parserStrictMode8.ts b/tests/cases/conformance/parser/ecmascript5/StrictMode/parserStrictMode8.ts
index 12f7f47431..7bfe896e7c 100644
--- a/tests/cases/conformance/parser/ecmascript5/StrictMode/parserStrictMode8.ts
+++ b/tests/cases/conformance/parser/ecmascript5/StrictMode/parserStrictMode8.ts
@@ -1,3 +1,4 @@
+// @skipDefaultLibCheck: false
 "use strict";
 function eval() {
 }
\ No newline at end of file
diff --git a/tests/cases/conformance/types/members/duplicateNumericIndexers.ts b/tests/cases/conformance/types/members/duplicateNumericIndexers.ts
index c2bfa38873..8b13cc5a67 100644
--- a/tests/cases/conformance/types/members/duplicateNumericIndexers.ts
+++ b/tests/cases/conformance/types/members/duplicateNumericIndexers.ts
@@ -1,3 +1,4 @@
+// @skipDefaultLibCheck: false
 // it is an error to have duplicate index signatures of the same kind in a type
 
 interface Number {
diff --git a/tests/cases/conformance/types/members/objectTypeHidingMembersOfExtendedObject.ts b/tests/cases/conformance/types/members/objectTypeHidingMembersOfExtendedObject.ts
index dbc5d05b2f..b18dc498bb 100644
--- a/tests/cases/conformance/types/members/objectTypeHidingMembersOfExtendedObject.ts
+++ b/tests/cases/conformance/types/members/objectTypeHidingMembersOfExtendedObject.ts
@@ -1,3 +1,4 @@
+// @skipDefaultLibCheck: false
 class A {
     foo: string;
 }
diff --git a/tests/cases/conformance/types/members/objectTypeWithStringIndexerHidingObjectIndexer.ts b/tests/cases/conformance/types/members/objectTypeWithStringIndexerHidingObjectIndexer.ts
index 106936ddcd..797ad2cb09 100644
--- a/tests/cases/conformance/types/members/objectTypeWithStringIndexerHidingObjectIndexer.ts
+++ b/tests/cases/conformance/types/members/objectTypeWithStringIndexerHidingObjectIndexer.ts
@@ -1,3 +1,4 @@
+// @skipDefaultLibCheck: false
 // object types can define string indexers that are more specific than the default 'any' that would be returned
 // no errors expected below