Remove tabStop feature

Source/core/input/EventHandler.h

 /*
  * Copyright (C) 2006, 2007, 2009, 2010, 2011 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 307 matching lines @@
     bool handleScrollGestureOnResizer(Node*, const PlatformGestureEvent&);
 
     bool passScrollGestureEventToWidget(const PlatformGestureEvent&, LayoutObject*);
 
     AutoscrollController* autoscrollController() const;
     bool panScrollInProgress() const;
     void setLastKnownMousePosition(const PlatformMouseEvent&);
 
     bool shouldTopControlsConsumeScroll(FloatSize) const;
 
-    // If the given element is a shadow host with tabStop = false, slide focus to its inner
-    // element. Returns true if the resulting focus is different from the given element.
-    bool slideFocusOnShadowHostIfNecessary(const Element&);
-
     // NOTE: If adding a new field to this class please ensure that it is
     // cleared in |EventHandler::clear()|.
 
     LocalFrame* const m_frame;
 
     bool m_mousePressed;
     bool m_capturesDragging;
     RefPtrWillBeMember<Node> m_mousePressNode;
 
     bool m_mouseDownMayStartSelect;
@@ skipping 83 matching lines @@
     // scroll sequence in this frame, or any child frames. Only used
     // with ScrollCustomization. If some delta has been consumed, a
     // scroll which shouldn't propagate can't cause any element to
     // scroll other than the |m_previousGestureScrolledNode|.
     bool m_deltaConsumedForScrollSequence;
 };
 
 } // namespace blink
 
 #endif // EventHandler_h