Rationalise hit testing in the new RenderNode world

sky/engine/core/view/EventCallback.h

 // 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.
 
 #ifndef SKY_ENGINE_CORE_VIEW_EVENTCALLBACK_H_
 #define SKY_ENGINE_CORE_VIEW_EVENTCALLBACK_H_
 
 namespace blink {
 class Event;
 
 class EventCallback {
 public:
     virtual ~EventCallback() { }
-    virtual bool handleEvent(Event* event) = 0;
+    virtual void handleEvent(Event* event) = 0;
 };
 
 }
 
 #endif  // SKY_ENGINE_CORE_VIEW_EVENTCALLBACK_H_