Fix emit for json file

src/compiler/emitter.ts

@@ -56,6 +56,10 @@ namespace ts {
     // So for JavaScript files, '.jsx' is only emitted if the input was '.jsx', and JsxEmit.Preserve.
     // For TypeScript, the only time to emit with a '.jsx' extension, is on JSX input, and JsxEmit.Preserve
     function getOutputExtension(sourceFile: SourceFile, options: CompilerOptions): Extension {
+        if (isJsonSourceFile(sourceFile)) {
+            return Extension.Json;
+        }
+
         if (options.jsx === JsxEmit.Preserve) {
             if (isSourceFileJavaScript(sourceFile)) {
                 if (fileExtensionIs(sourceFile.fileName, Extension.Jsx)) {
@@ -1615,7 +1619,9 @@ namespace ts {
 
         function emitExpressionStatement(node: ExpressionStatement) {
             emitExpression(node.expression);
-            writeSemicolon();
+            if (!isJsonSourceFile(currentSourceFile)) {
+                writeSemicolon();
+            }
         }
 
         function emitIfStatement(node: IfStatement) {

src/harness/harness.ts

@@ -1802,6 +1802,10 @@ namespace Harness {
             return ts.endsWith(fileName, ts.Extension.Jsx);
         }
 
+        export function isJSON(fileName: string) {
+            return ts.endsWith(fileName, ts.Extension.Json);
+        }
+
         export function isJSMap(fileName: string) {
             return ts.endsWith(fileName, ".js.map") || ts.endsWith(fileName, ".jsx.map");
         }
@@ -1822,7 +1826,7 @@ namespace Harness {
                         // .d.ts file, add to declFiles emit
                         this.declFilesCode.push(emittedFile);
                     }
-                    else if (isJS(emittedFile.fileName) || isJSX(emittedFile.fileName)) {
+                    else if (isJS(emittedFile.fileName) || isJSX(emittedFile.fileName) || isJSON(emittedFile.fileName)) {
                         // .js file, add to files
                         this.files.push(emittedFile);
                     }

tests/baselines/reference/requireOfJsonFile.js

@@ -15,11 +15,11 @@ if (x) {
     "b": "hello"
 }
 
-//// [b.js]
+//// [b.json]
 {
     "a": true,
     "b": "hello"
-};
+}
 //// [file1.js]
 "use strict";
 exports.__esModule = true;

tests/cases/compiler/requireOfJsonFile.ts

@@ -1,4 +1,5 @@
 // @module: commonjs
+// @outdir: out/
 
 // @Filename: file1.ts
 import b1 = require('./b');