Remove duplicate startsWith and endsWith functions

src/compiler/core.ts

@@ -900,7 +900,7 @@ namespace ts {
     }
 
     export function fileExtensionIs(path: string, extension: string): boolean {
-        return stringEndsWith(path, extension);
+        return path.length > extension.length && endsWith(path, extension);
     }
 
     export function fileExtensionIsAny(path: string, extensions: string[]): boolean {
@@ -913,18 +913,6 @@ namespace ts {
         return false;
     }
 
-    // Should act like String.prototype.startsWith
-    export function stringStartsWith(s: string, start: string): boolean {
-        return s.length > start.length && s.substr(0, start.length) === start;
-    }
-
-    // Should act like String.prototype.endsWith
-    export function stringEndsWith(s: string, end: string): boolean {
-        const sLen = s.length;
-        const endLen = end.length;
-        return sLen > endLen && s.substr(sLen - endLen, endLen) === end;
-    }
-
     // Reserved characters, forces escaping of any non-word (or digit), non-whitespace character.
     // It may be inefficient (we could just match (/[-[\]{}()*+?.,\\^$|#\s]/g), but this is future
     // proof.

src/harness/harness.ts

@@ -1377,31 +1377,27 @@ namespace Harness {
             writeByteOrderMark: boolean;
         }
 
-        function stringEndsWith(str: string, end: string) {
-            return str.substr(str.length - end.length) === end;
-        }
-
         export function isTS(fileName: string) {
-            return stringEndsWith(fileName, ".ts");
+            return ts.endsWith(fileName, ".ts");
         }
 
         export function isTSX(fileName: string) {
-            return stringEndsWith(fileName, ".tsx");
+            return ts.endsWith(fileName, ".tsx");
         }
 
         export function isDTS(fileName: string) {
-            return stringEndsWith(fileName, ".d.ts");
+            return ts.endsWith(fileName, ".d.ts");
         }
 
         export function isJS(fileName: string) {
-            return stringEndsWith(fileName, ".js");
+            return ts.endsWith(fileName, ".js");
         }
         export function isJSX(fileName: string) {
-            return stringEndsWith(fileName, ".jsx");
+            return ts.endsWith(fileName, ".jsx");
         }
 
         export function isJSMap(fileName: string) {
-            return stringEndsWith(fileName, ".js.map") || stringEndsWith(fileName, ".jsx.map");
+            return ts.endsWith(fileName, ".js.map") || ts.endsWith(fileName, ".jsx.map");
         }
 
         /** Contains the code and errors of a compilation and some helper methods to check its status. */

src/services/patternMatcher.ts

@@ -514,16 +514,6 @@ namespace ts {
         return str === str.toLowerCase();
     }
 
-    function startsWith(string: string, search: string) {
-        for (let i = 0, n = search.length; i < n; i++) {
-            if (string.charCodeAt(i) !== search.charCodeAt(i)) {
-                return false;
-            }
-        }
-
-        return true;
-    }
-
     // Assumes 'value' is already lowercase.
     function indexOfIgnoringCase(string: string, value: string): number {
         for (let i = 0, n = string.length - value.length; i <= n; i++) {