Convert dart_utils.js to input_sdk/lib/_internal/utils.dart (#310)

lib/src/runner/runtime_utils.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// JS runtime files utilities used by dartdevrun.
 library dev_compiler.src.runner.runtime_utils;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:path/path.dart';
 
 import '../compiler.dart' show defaultRuntimeFiles;
 import '../options.dart';
 import 'file_utils.dart';
 
 /// In node.js / io.js, these modules need to be aliased globally
 /// (e.g. `var foo = require('./path/to/foo.js')`).
 /// TODO(ochafik): Investigate alternative module / alias patterns.
 const _ALIASED_RUNTIME_FILES = const {
   'dart_library.js': 'dart_library',
-  'dart_utils.js': 'dart_utils',
+  'dart/_utils.js': 'dart_utils',
 };
 
 /// If [path] is a runtime file with an alias, returns that alias, otherwise
 /// returns null.
 String getRuntimeFileAlias(CompilerOptions options, File file) =>
     file.absolute.path.startsWith(_getRuntimeDir(options).absolute.path)
         ? _ALIASED_RUNTIME_FILES[basename(file.path)]
         : null;
 
 Directory _getRuntimeDir(CompilerOptions options) => new Directory(
@@ skipping 15 matching lines @@
   return files
     ..sort((File a, File b) {
       int pa = getPriorityIndex(a), pb = getPriorityIndex(b);
       return pa != pb ? (pa - pb) : a.path.compareTo(b.path);
     });
 }
 
 /// TODO(ochafik): Split / reuse [AbstractCompiler.getModuleName].
 String getMainModuleName(CompilerOptions options) =>
     basename(withoutExtension(options.inputs.single));