Add test to verify #26669 where declaration output is incorrect when declaration flag is not set explicitly in options

tests/baselines/reference/declarationEmitWithComposite.js

@@ -0,0 +1,14 @@
+//// [test.ts]
+interface Foo {
+    x: number;
+}
+export default Foo;
+
+
+//// [/foo/out/test.js]
+"use strict";
+exports.__esModule = true;
+
+
+//// [/foo/out/test.d.ts]
+export default Foo;

tests/baselines/reference/declarationEmitWithComposite.symbols

@@ -0,0 +1,10 @@
+=== /foo/test.ts ===
+interface Foo {
+>Foo : Symbol(Foo, Decl(test.ts, 0, 0))
+
+    x: number;
+>x : Symbol(Foo.x, Decl(test.ts, 0, 15))
+}
+export default Foo;
+>Foo : Symbol(Foo, Decl(test.ts, 0, 0))
+

tests/baselines/reference/declarationEmitWithComposite.types

@@ -0,0 +1,8 @@
+=== /foo/test.ts ===
+interface Foo {
+    x: number;
+>x : number
+}
+export default Foo;
+>Foo : Foo
+

tests/cases/compiler/declarationEmitWithComposite.ts

@@ -0,0 +1,13 @@
+// @composite: true
+// @fullEmitPaths: true
+
+// @filename: /foo/tsconfig.json
+{
+    "compilerOptions": { "composite": true, "outDir": "out" }
+}
+
+// @filename: /foo/test.ts
+interface Foo {
+    x: number;
+}
+export default Foo;