Rename watchPerformance to watch

sky/sdk/lib/widgets/drawer.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:sky' as sky;
 
 import 'package:sky/animation/animation_performance.dart';
 import 'package:sky/animation/curves.dart';
 import 'package:sky/theme/shadows.dart';
 import 'package:sky/widgets/animated_component.dart';
@@ skipping 87 matching lines @@
       performance.fling(velocity: velocityX / _kWidth);
   }
 }
 
 class Drawer extends AnimatedComponent {
   Drawer({
     String key,
     this.controller,
     this.children,
     this.level: 0
-  }) : super(key: key) {
-    watchPerformance(controller.performance);
-  }
+  }) : super(key: key);
 
   List<Widget> children;
   int level;
   DrawerController controller;
 
+  void initState() {
+    watch(controller.performance);
+  }
+
   void syncFields(Drawer source) {
     children = source.children;
     level = source.level;
     controller = source.controller;
     super.syncFields(source);
   }
 
   // TODO(mpcomplete): the animation system should handle building, maybe? Or
   // at least setting the transform. Figure out how this could work for things
   // like fades, slides, rotates, pinch, etc.
@@ skipping 20 matching lines @@
       child: new Stack([ mask, content ]),
       onPointerDown: controller.handlePointerDown,
       onPointerMove: controller.handlePointerMove,
       onPointerUp: controller.handlePointerUp,
       onPointerCancel: controller.handlePointerCancel,
       onGestureFlingStart: controller.handleFlingStart
     );
   }
 
 }