Remove Collection, Collections and clean up List/Set/Queue implementations of retain/remove.

sdk/lib/_internal/compiler/implementation/mirrors/mirrors.dart

 // Copyright (c) 2012, 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.
 
 library mirrors;
 
 import 'dart:async';
 import 'dart:uri';
 
 // TODO(rnystrom): Use "package:" URL (#4968).
@@ skipping 151 matching lines @@
   int get length;
 }
 
 /**
  * Specialized [InstanceMirror] used for reflection on constant maps.
  */
 abstract class MapInstanceMirror implements InstanceMirror {
   /**
    * Returns a collection containing all the keys in the map.
    */
-  Collection<String> get keys;
+  Iterable<String> get keys;
 
   /**
    * Returns a future on the instance mirror of the value for the given key or
    * null if key is not in the map.
    */
   Future<InstanceMirror> operator[](String key);
 
   /**
    * The number of {key, value} pairs in the map.
    */
@@ skipping 508 matching lines @@
   /**
    * Returns the URI where the source originated.
    */
   Uri get sourceUri;
 
   /**
    * Returns the text of this source.
    */
   String get sourceText;
 }