All strong mode cleaning of dart2js.

pkg/compiler/lib/src/helpers/track_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.
 
 /**
  * The track map is a simple wrapper around a map that keeps track
  * of the 'final' size of maps grouped by description. It allows
  * determining the distribution of sizes for a specific allocation
  * site and it can be used like this:
  *
@@ skipping 39 matching lines @@
     });
   }
 
   int get length => _map.length;
   bool get isEmpty => _map.isEmpty;
   bool get isNotEmpty => _map.isNotEmpty;
 
   Iterable<K> get keys => _map.keys;
   Iterable<V> get values => _map.values;
 
-  bool containsKey(K key) => _map.containsKey(key);
-  bool containsValue(V value) => _map.containsValue(value);
+  bool containsKey(Object key) => _map.containsKey(key);
+  bool containsValue(Object value) => _map.containsValue(value);
 
-  V operator [](K key) => _map[key];
+  V operator [](Object key) => _map[key];
   String toString() => _map.toString();
 
   void forEach(void action(K key, V value)) {
     _map.forEach(action);
   }
 
   void operator []=(K key, V value) {
     if (!_map.containsKey(key)) {
       _notifyLengthChanged(1);
       _map[key] = value;
@@ skipping 28 matching lines @@
     int newLength = oldLength + delta;
     _counts[oldLength]--;
     if (newLength < _counts.length) {
       _counts[newLength]++;
     } else {
       _counts.add(1);
       assert(newLength == _counts.length - 1);
     }
   }
 }