WIP: prefer using EphemeralRange for SpellChecker.

Source/core/dom/Range.h

 /*
  * (C) 1999 Lars Knoll (knoll@kde.org)
  * (C) 2000 Gunnstein Lye (gunnstein@netcom.no)
  * (C) 2000 Frederik Holljen (frederik.holljen@hig.no)
  * (C) 2001 Peter Kelly (pmk@post.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 46 matching lines @@
     , public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static PassRefPtrWillBeRawPtr<Range> create(Document&);
     static PassRefPtrWillBeRawPtr<Range> create(Document&, Node* startContainer, int startOffset, Node* endContainer, int endOffset);
     static PassRefPtrWillBeRawPtr<Range> create(Document&, const Position&, const Position&);
     static PassRefPtrWillBeRawPtr<Range> createAdjustedToTreeScope(const TreeScope&, const Position&);
 #if !ENABLE(OILPAN) || !defined(NDEBUG)
     ~Range();
 #endif
+    void dispose();

[yosin_UTC9, 2015/09/10 01:58:39]

I'm still in double to introduce |Range::dispose()|. Or, it is too early
to introduce. For spell checker, we don't need to use |dispose()|, since
we can replace all of |Range| usage to |EphmeralRange|.

If we really need to have |Range::dispose()|, let's remove "noop" mark
from |Range:detach()| and use |detach()|.

User script may register "non-needed" |Range| objects to |Document| too.

[sof, 2015/09/10 05:59:02]

Please see 


https://groups.google.com/a/chromium.org/d/msg/oilpan-reviews/bXesw9EnP3Q/Nd7...

for motivation on why dispose() is needed. Rewriting all uses of Range to be
EphemeralRange, if that's possible in the face of tree mutations, isn't a
practical option at this stage.

dispose() is our preferred naming for these operations.

 
     Document& ownerDocument() const { ASSERT(m_ownerDocument); return *m_ownerDocument.get(); }
     Node* startContainer() const { return m_start.container(); }
     int startOffset() const { return m_start.offset(); }
     Node* endContainer() const { return m_end.container(); }
     int endOffset() const { return m_end.offset(); }
 
     bool collapsed() const { return m_start == m_end; }
 
     Node* commonAncestorContainer() const;
@@ skipping 108 matching lines @@
 CORE_EXPORT bool areRangesEqual(const Range*, const Range*);
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showTree(const blink::Range*);
 #endif
 
 #endif // Range_h