Move dart2js from sdk/lib/_internal/compiler to pkg/compiler

sdk/lib/_internal/compiler/implementation/helpers/expensive_map.dart

-// Copyright (c) 2013, 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.
-
-part of dart2js.helpers;
-
-/**
- * The expensive map is a data structure useful for tracking down
- * excessive memory usage due to large maps. It acts as an ordinary
- * hash map, but it uses 10 times more memory (by default).
- */
-class ExpensiveMap<K, V> implements Map<K, V> {
-
-  final List _maps;
-
-  ExpensiveMap([int copies = 10]) : _maps = new List(copies) {
-    assert(copies > 0);
-    for (int i = 0; i < _maps.length; i++) {
-      _maps[i] = new Map<K, V>();
-    }
-  }
-
-  int get length => _maps[0].length;
-  bool get isEmpty => _maps[0].isEmpty;
-  bool get isNotEmpty => _maps[0].isNotEmpty;
-
-  Iterable<K> get keys => _maps[0].keys;
-  Iterable<V> get values => _maps[0].values;
-
-  bool containsKey(K key) => _maps[0].containsKey(key);
-  bool containsValue(V value) => _maps[0].containsValue(value);
-
-  V operator[](K key) => _maps[0][key];
-
-  void forEach(void action(K key, V value)) {
-    _maps[0].forEach(action);
-  }
-
-  void operator[]=(K key, V value) {
-    for (int i = 0; i < _maps.length; i++) {
-      _maps[i][key] = value;
-    }
-  }
-
-  V putIfAbsent(K key, V ifAbsent()) {
-    if (containsKey(key)) return this[key];
-    V value = ifAbsent();
-    this[key] = value;
-    return value;
-  }
-
-  void addAll(Map<K, V> other) {
-    for (int i = 0; i < _maps.length; i++) {
-      _maps[i].addAll(other);
-    }
-  }
-
-  V remove(Object key) {
-    V result = _maps[0].remove(key);
-    for (int i = 1; i < _maps.length; i++) {
-      _maps[i].remove(key);
-    }
-    return result;
-  }
-
-  void clear() {
-    for (int i = 0; i < _maps.length; i++) {
-      _maps[i].clear();
-    }
-  }
-
-  String toString() => "expensive(${_maps[0]}x${_maps.length})";
-}