Remove dead isLocalPort from the VM mirrors implementation.

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";
 
 final emptyList = new UnmodifiableListView([]);
 final emptyMap = new _UnmodifiableMapView({});
@@ skipping 1399 matching lines @@
     }
     return this.simpleName == other.simpleName;
   }
 
   int get hashCode => simpleName.hashCode;
 
   String toString() => "TypeMirror on '${_n(simpleName)}'";
 }
 
 class _Mirrors {
-  // Does a port refer to our local isolate?
-  static bool isLocalPort(SendPort port) native 'Mirrors_isLocalPort';
-
   static MirrorSystem _currentMirrorSystem = null;
 
   // Creates a new local MirrorSystem.
   static MirrorSystem makeLocalMirrorSystem()
       native 'Mirrors_makeLocalMirrorSystem';
 
   // The MirrorSystem for the current isolate.
   static MirrorSystem currentMirrorSystem() {
     if (_currentMirrorSystem == null) {
       _currentMirrorSystem = makeLocalMirrorSystem();
@@ skipping 33 matching lines @@
     if (typeMirror == null) {
       typeMirror = makeLocalTypeMirror(key);
       _instanitationCache[key] = typeMirror;
       if (typeMirror is ClassMirror && !typeMirror._isGeneric) {
         _declarationCache[key] = typeMirror;
       }
     }
     return typeMirror;
   }
 }