Re-add snap-back behavior (Blink side)

public/web/WebInputEvent.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 279 matching lines @@
     BLINK_EXPORT void setKeyIdentifierFromWindowsKeyCode();
 
     static int windowsKeyCodeWithoutLocation(int keycode);
     static int locationModifiersFromWindowsKeyCode(int keycode);
 };
 
 // WebMouseEvent --------------------------------------------------------------
 
 class WebMouseEvent : public WebInputEvent {
 public:
-    // These values defined for WebCore::MouseButton
     enum Button {
         ButtonNone = -1,
         ButtonLeft,
         ButtonMiddle,
         ButtonRight
     };
 
     Button button;
     int x;
     int y;
@@ skipping 171 matching lines @@
         , targetTouchesLength(0)
     {
     }
 };
 
 #pragma pack(pop)
 
 } // namespace blink
 
 #endif