Canvas2d: Implement rerouting event by hit region's control.

third_party/WebKit/Source/modules/canvas2d/MouseEventHitRegion.cpp

Index: third_party/WebKit/Source/modules/canvas2d/MouseEventHitRegion.cpp
diff --git a/third_party/WebKit/Source/modules/canvas2d/MouseEventHitRegion.cpp b/third_party/WebKit/Source/modules/canvas2d/MouseEventHitRegion.cpp
index 71b628416551ee3daad5376353fa6165ad38da7b..72bb1947d783c3244ec4149d7c4ceef566894110 100644
--- a/third_party/WebKit/Source/modules/canvas2d/MouseEventHitRegion.cpp
+++ b/third_party/WebKit/Source/modules/canvas2d/MouseEventHitRegion.cpp
@@ -5,17 +5,12 @@
 #include "modules/canvas2d/MouseEventHitRegion.h"
 
 #include "core/events/MouseEvent.h"
-#include "core/html/HTMLCanvasElement.h"
 
 namespace blink {
 
 String MouseEventHitRegion::region(MouseEvent& event)
 {
-    if (!event.target() || !isHTMLCanvasElement(event.target()->toNode()))
-        return String();
-
-    HTMLCanvasElement* canvas = toHTMLCanvasElement(event.target()->toNode());
-    return regionIdFromAbsoluteLocation(*canvas, event.absoluteLocation());
+    return event.region();
 }
 
 } // namespace blink