Merge pull request #14519 from Microsoft/gulp_lint

Fix tslint compilation in gulp

Author: Andy

Gulpfile.ts

@@ -960,7 +960,7 @@ gulp.task("update-sublime", "Updates the sublime plugin's tsserver", ["local", s
 });
 
 gulp.task("build-rules", "Compiles tslint rules to js", () => {
-    const settings: tsc.Settings = getCompilerSettings({ module: "commonjs" }, /*useBuiltCompiler*/ false);
+    const settings: tsc.Settings = getCompilerSettings({ module: "commonjs", "lib": ["es6"] }, /*useBuiltCompiler*/ false);
     const dest = path.join(builtLocalDirectory, "tslint");
     return gulp.src("scripts/tslint/**/*.ts")
         .pipe(newer({