Remove unimplemented nodeUnderMouse() method from EventHandler.h

nodeUnderMouse function is unimplemented in the complete code, so removing it.

Review URL: https://codereview.chromium.org/297293007

git-svn-id: svn://svn.chromium.org/blink/trunk@175119 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/page/EventHandler.h

@@ -252,8 +252,6 @@ private:
 
     void invalidateClick();
 
-    Node* nodeUnderMouse() const;
-
     void updateMouseEventTargetNode(Node*, const PlatformMouseEvent&, bool fireMouseOverOut);
 
     MouseEventWithHitTestResults prepareMouseEvent(const HitTestRequest&, const PlatformMouseEvent&);