Cleanup references to the old DDC repo

pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/generators.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.
 
 /// 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.
+/// See #27315 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.
 part of dart._runtime;
 
 final _jsIterator = JS('', 'Symbol("_jsIterator")');
 final _current = JS('', 'Symbol("_current")');
 
 syncStar(gen, E, @rest args) => JS('', '''(() => {
   const SyncIterable_E = ${getGenericClass(SyncIterable)}($E);
   return new SyncIterable_E($gen, $args);
@@ skipping 195 matching lines @@
       this.controller.addError(error, stackTrace);
     }
   }
 ''');
 
 /// Returns a Stream of T implemented by an async* function. */
 ///
 asyncStar(gen, T, @rest args) => JS('', '''(() => {
   return new $_AsyncStarStreamController($gen, $T, $args).controller.stream;
 })()''');