Cover an example of equality and hashCode for each type of mirror.

runtime/lib/mirrors_impl.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.
 
 // VM-specific implementation of the dart:mirrors library.
 
 import "dart:collection";
 
 // These values are allowed to be passed directly over the wire.
 bool _isSimpleValue(var value) {
@@ skipping 121 matching lines @@
     if (_voidType == null) {
       _voidType = new _SpecialTypeMirrorImpl('void');
     }
     return _voidType;
   }
 
   String toString() => "MirrorSystem for isolate '${isolate.debugName}'";
 }
 
 abstract class _LocalMirrorImpl implements Mirror {
-  int get hashCode {
-    throw new UnimplementedError('Mirror.hashCode is not implemented');
-  }
-
   // Local mirrors always return the same MirrorSystem.  This field
   // is more interesting once we implement remote mirrors.
   MirrorSystem get mirrors => _Mirrors.currentMirrorSystem();
 }
 
 class _LocalIsolateMirrorImpl extends _LocalMirrorImpl
     implements IsolateMirror {
   _LocalIsolateMirrorImpl(this.debugName, this.rootLibrary);
 
   final String debugName;
@@ skipping 1305 matching lines @@
     if (typeMirror == null) {
       typeMirror = makeLocalTypeMirror(key);
       _instanitationCache[key] = typeMirror;
       if (typeMirror is ClassMirror && !typeMirror._isGeneric) {
         _declarationCache[key] = typeMirror;
       }
     }
     return typeMirror;
   }
 }