unfork DDC's copy of most SDK libraries

pkg/dev_compiler/tool/input_sdk/private/linked_hash_map.dart

 // Copyright (c) 2014, 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.
 
 // Efficient JavaScript based implementation of a linked hash map used as a
 // backing map for constant maps and the [LinkedHashMap] patch
 
 part of dart._js_helper;
 
 // DDC-specific, just use Object-backed maps
@@ skipping 364 matching lines @@
 class LinkedHashMapCell<K, V> {
   final dynamic/*=K*/ hashMapCellKey;
   dynamic/*=V*/ hashMapCellValue;
 
   LinkedHashMapCell/*<K, V>*/ _next;
   LinkedHashMapCell/*<K, V>*/ _previous;
 
   LinkedHashMapCell(this.hashMapCellKey, this.hashMapCellValue);
 }
 
-class LinkedHashMapKeyIterable<E> extends Iterable<E>
-    implements EfficientLength {
+class LinkedHashMapKeyIterable<E> extends EfficientLengthIterable<E> {
   final dynamic/*=JsLinkedHashMap<E, dynamic>*/ _map;
   LinkedHashMapKeyIterable(this._map);
 
   int get length => _map._length;
   bool get isEmpty => _map._length == 0;
 
   Iterator<E> get iterator {
     return new LinkedHashMapKeyIterator<E>(_map, _map._modifications);
   }
 
@@ skipping 32 matching lines @@
     } else if (_cell == null) {
       _current = null;
       return false;
     } else {
       _current = _cell.hashMapCellKey;
       _cell = _cell._next;
       return true;
     }
   }
 }