Replace forward class declarations of VisiblePosition to include directives

Source/core/editing/VisibleUnits.h

 /*
  * Copyright (C) 2004 Apple Computer, 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 11 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef VisibleUnits_h
 #define VisibleUnits_h
 
 #include "core/CoreExport.h"
 #include "core/editing/EditingBoundary.h"
 #include "core/editing/PositionWithAffinity.h"
+#include "core/editing/VisiblePosition.h"
 #include "platform/text/TextDirection.h"
 
 namespace blink {
 
 class LayoutRect;
 class LayoutUnit;
 class LayoutObject;
 class Node;
-class VisiblePosition;
 class IntPoint;
 class InlineBox;
 class LocalFrame;
 
 enum EWordSide { RightWordIfOnBoundary = false, LeftWordIfOnBoundary = true };
 
 struct InlineBoxPosition {
     InlineBox* inlineBox;
     int offsetInBox;
 
@@ skipping 106 matching lines @@
 
 // Returns a hit-tested VisiblePosition for the given point in contents-space
 // coordinates.
 CORE_EXPORT VisiblePosition visiblePositionForContentsPoint(const IntPoint&, LocalFrame*);
 
 CORE_EXPORT bool rendersInDifferentPosition(const Position&, const Position&);
 
 } // namespace blink
 
 #endif // VisibleUnits_h