Remove dart:mirrors from Sky framework

sky/sdk/lib/widgets/widget.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'dart:async';
 import 'dart:collection';
-import 'dart:mirrors';
 import 'dart:sky' as sky;
 
 import 'package:sky/mojo/activity.dart' as activity;
 
 import '../base/hit_test.dart';
 import '../rendering/box.dart';
 import '../rendering/object.dart';
 import '../rendering/sky_binding.dart';
 
 export '../rendering/box.dart' show BoxConstraints, BoxDecoration, Border, BorderSide, EdgeDims;
@@ skipping 107 matching lines @@
   // This is called immediately before _sync().
   // Component._retainStatefulNodeIfPossible() calls syncFields().
   bool _retainStatefulNodeIfPossible(Widget old) => false;
 
   void _sync(Widget old, dynamic slot);
   void updateSlot(dynamic newSlot);
   // 'slot' is the identifier that the ancestor RenderObjectWrapper uses to know
   // where to put this descendant. If you just defer to a child, then make sure
   // to pass them the slot.
 
-  Widget findAncestor(Type targetType) {
+  Widget findAncestorRenderObjectWrapper() {
     var ancestor = _parent;
-    while (ancestor != null && !reflectClass(ancestor.runtimeType).isSubtypeOf(reflectClass(targetType)))
+    while (ancestor != null && ancestor is! RenderObjectWrapper)
       ancestor = ancestor._parent;
     return ancestor;
   }
 
   void remove() {
     _root = null;
     setParent(null);
   }
 
   void removeChild(Widget node) {
@@ skipping 509 matching lines @@
   void insertChildRoot(RenderObjectWrapper child, dynamic slot);
   void detachChildRoot(RenderObjectWrapper child);
 
   void _sync(RenderObjectWrapper old, dynamic slot) {
     // TODO(abarth): We should split RenderObjectWrapper into two pieces so that
     //               RenderViewObject doesn't need to inherit all this code it
     //               doesn't need.
     assert(parent != null || this is RenderViewWrapper);
     if (old == null) {
       _root = createNode();
-      _ancestor = findAncestor(RenderObjectWrapper);
+      _ancestor = findAncestorRenderObjectWrapper();
       if (_ancestor is RenderObjectWrapper)
         _ancestor.insertChildRoot(this, slot);
     } else {
       assert(old is RenderObjectWrapper);
       _root = old.root;
       _ancestor = old._ancestor;
     }
     assert(_root == root); // in case a subclass reintroduces it
     assert(root != null);
     assert(mounted);
@@ skipping 431 matching lines @@
     if (root.parent == null) {
       // we haven't attached it yet
       assert(_container.child == null);
       _container.child = root;
     }
     assert(root.parent == _container);
   }
 
   Widget build() => builder();
 }