Reduce forward declarations in core/dom

Source/core/editing/VisiblePosition.h

 /*
  * Copyright (C) 2004, 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 30 matching lines @@
 
 // Callers who do not know where on the line the position is,
 // but would like UPSTREAM if at a line break or DOWNSTREAM
 // otherwise, need a clear way to specify that.  The
 // constructors auto-correct UPSTREAM to DOWNSTREAM if the
 // position is not at a line break.
 #define VP_UPSTREAM_IF_POSSIBLE UPSTREAM
 
 class InlineBox;
 class Node;
+class Range;
 
 class VisiblePosition FINAL {
     DISALLOW_ALLOCATION();
 public:
     // NOTE: UPSTREAM affinity will be used only if pos is at end of a wrapped line,
     // otherwise it will be converted to DOWNSTREAM
     VisiblePosition() : m_affinity(VP_DEFAULT_AFFINITY) { }
     explicit VisiblePosition(const Position&, EAffinity = VP_DEFAULT_AFFINITY);
     explicit VisiblePosition(const PositionWithAffinity&);
 
@@ skipping 81 matching lines @@
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showTree(const WebCore::VisiblePosition*);
 void showTree(const WebCore::VisiblePosition&);
 #endif
 
 #endif // VisiblePosition_h