Dont default to CommonJS modules for ES6 target

(cherry picked from commit 4a67dc5)

Author: billti

src/compiler/checker.ts

@@ -49,7 +49,7 @@ namespace ts {
 
  const compilerOptions = host.getCompilerOptions();
  const languageVersion = compilerOptions.target || ScriptTarget.ES3;
- const modulekind = typeof compilerOptions.module === "number" ? compilerOptions.module : languageVersion === ScriptTarget.ES6 ? ModuleKind.ES6 : ModuleKind.CommonJS;
+ const modulekind = getEmitModuleKind(compilerOptions);
  const allowSyntheticDefaultImports = typeof compilerOptions.allowSyntheticDefaultImports !== "undefined" ? compilerOptions.allowSyntheticDefaultImports : modulekind === ModuleKind.System;
 
  const emitResolver = createResolver();

src/compiler/commandLineParser.ts

@@ -606,7 +606,6 @@ namespace ts {
  const options: CompilerOptions = {};
  const errors: Diagnostic[] = [];
 
- options.module = ModuleKind.CommonJS;
  if (configFileName && getBaseFileName(configFileName) === "jsconfig.json") {
  options.allowJs = true;
  }

src/compiler/program.ts

@@ -1652,7 +1652,7 @@ namespace ts {
 
  const firstExternalModuleSourceFile = forEach(files, f => isExternalModule(f) ? f : undefined);
  if (options.isolatedModules) {
- if (!options.module && languageVersion < ScriptTarget.ES6) {
+ if (options.module === ModuleKind.None && languageVersion < ScriptTarget.ES6) {
  programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Option_isolatedModules_can_only_be_used_when_either_option_module_is_provided_or_option_target_is_ES2015_or_higher));
  }
 
@@ -1662,7 +1662,7 @@ namespace ts {
  programDiagnostics.add(createFileDiagnostic(firstNonExternalModuleSourceFile, span.start, span.length, Diagnostics.Cannot_compile_namespaces_when_the_isolatedModules_flag_is_provided));
  }
  }
- else if (firstExternalModuleSourceFile && languageVersion < ScriptTarget.ES6 && !options.module) {
+ else if (firstExternalModuleSourceFile && languageVersion < ScriptTarget.ES6 && options.module === ModuleKind.None) {
  // We cannot use createDiagnosticFromNode because nodes do not have parents yet
  const span = getErrorSpanForNode(firstExternalModuleSourceFile, firstExternalModuleSourceFile.externalModuleIndicator);
  programDiagnostics.add(createFileDiagnostic(firstExternalModuleSourceFile, span.start, span.length, Diagnostics.Cannot_compile_modules_unless_the_module_flag_is_provided_Consider_setting_the_module_compiler_option_in_a_tsconfig_json_file));

src/harness/harness.ts

@@ -966,7 +966,6 @@ namespace Harness {
 
  const options: ts.CompilerOptions & HarnessOptions = compilerOptions ? ts.clone(compilerOptions) : { noResolve: false };
  options.target = options.target || ts.ScriptTarget.ES3;
- options.module = options.module || ts.ModuleKind.None;
  options.newLine = options.newLine || ts.NewLineKind.CarriageReturnLineFeed;
  options.noErrorTruncation = true;
  options.skipDefaultLibCheck = true;

src/services/services.ts

@@ -1713,7 +1713,6 @@ namespace ts {
  // Always default to "ScriptTarget.ES5" for the language service
  return {
  target: ScriptTarget.ES5,
- module: ModuleKind.CommonJS,
  jsx: JsxEmit.Preserve
  };
  }