Move isVisuallyEquivalentCandidate() to VisibleUnits.{cpp,h} from Position.{cpp,h}

Source/core/editing/Position.h

 /*
  * Copyright (C) 2004, 2006, 2008 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 424 matching lines @@
 CORE_EXPORT InlineBoxPosition computeInlineBoxPosition(const PositionInComposedTree&, TextAffinity, TextDirection primaryDirection);
 
 // TODO(yosin) We should move |inRenderedText()| to "VisibleUnits.h" for
 // reduce dependency of |LayoutObject| in |Position| class.
 CORE_EXPORT bool inRenderedText(const Position&);
 CORE_EXPORT bool inRenderedText(const PositionInComposedTree&);
 
 CORE_EXPORT int uncheckedPreviousOffset(const Node*, int current);
 CORE_EXPORT int uncheckedNextOffset(const Node*, int current);
 
-// TODO(yosin) We should move |isVisuallyEquivalentCandidate()| to
-// "VisibleUnits.cpp" to reduce |LayoutObject| dependency in "Position.cpp".
-CORE_EXPORT bool isVisuallyEquivalentCandidate(const Position&);
-CORE_EXPORT bool isVisuallyEquivalentCandidate(const PositionInComposedTree&);
-
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showTree(const blink::Position&);
 void showTree(const blink::Position*);
 #endif
 
 #endif // Position_h