Move runtime js files down to lib/runtime/dart

lib/runtime/dart/_generators.js

 // 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.
 
 /**
  * This library adapts ES6 generators to implement Dart's async/await.
  *
  * It's designed to interact with Dart's Future/Stream and follow Dart
  * async/await semantics.
  *
  * See https://github.com/dart-lang/dev_compiler/issues/245 for ideas on
  * reconciling Dart's Future and ES6 Promise.
  *
  * Inspired by `co`: https://github.com/tj/co/blob/master/index.js, which is a
  * stepping stone for proposed ES7 async/await, and uses ES6 Promises.
  */
-dart_library.library('dart_runtime/_generators', null, /* Imports */[
+dart_library.library('dart/_generators', null, /* Imports */[
 ], /* Lazy Imports */[
-  'dart_runtime/_operations',
+  'dart/_operations',
   'dart/_js_helper',
   'dart/core',
   'dart/collection',
   'dart/async'
 ], function(exports, _operations, _js_helper, core, collection, async) {
   'use strict';
 
   const _jsIterator = Symbol('_jsIterator');
   const _current = Symbol('_current');
 
@@ skipping 195 matching lines @@
       this.controller.addError(error, stackTrace);
     }
   }
 
   /** Returns a Stream of T implemented by an async* function. */
   function asyncStar(gen, T, ...args) {
     return new _AsyncStarStreamController(gen, T, args).controller.stream;
   }
   exports.asyncStar = asyncStar;
 });