Introduce Range::dispose() for prompt detachment from owner Document.

Source/core/dom/Range.cpp

 /*
  * (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, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Motorola Mobility. 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
@@ skipping 117 matching lines @@
     // Always detach (even if we've already detached) to fix https://bugs.webkit.org/show_bug.cgi?id=26044
     m_ownerDocument->detachRange(this);
 #endif
 
 #ifndef NDEBUG
     rangeCounter.decrement();
 #endif
 }
 #endif
 
+void Range::dispose()
+{
+#if ENABLE(OILPAN)
+    // A prompt detach from the owning Document helps avoid GC overhead.
+    m_ownerDocument->detachRange(this);
+#endif
+}
+
 void Range::setDocument(Document& document)
 {
     ASSERT(m_ownerDocument != document);
     ASSERT(m_ownerDocument);
     m_ownerDocument->detachRange(this);
     m_ownerDocument = &document;
     m_start.setToStartOfNode(document);
     m_end.setToStartOfNode(document);
     m_ownerDocument->attachRange(this);
 }
@@ skipping 1534 matching lines @@
 {
     if (range && range->boundaryPointsValid()) {
         range->startContainer()->showTreeAndMark(range->startContainer(), "S", range->endContainer(), "E");
         fprintf(stderr, "start offset: %d, end offset: %d\n", range->startOffset(), range->endOffset());
     } else {
         fprintf(stderr, "Cannot show tree if range is null, or if boundary points are invalid.\n");
     }
 }
 
 #endif