boundaryTextInserted/Removed() should not call markValid() for irrelavent changes

third_party/WebKit/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 1368 matching lines @@
     // FIXME: Once DOMNodeRemovedFromDocument mutation event removed, we
     // should change following if-statement to DCHECK(!node->parentNode).
     if (!node.parentNode())
         return;
     boundaryNodeWillBeRemoved(m_start, node);
     boundaryNodeWillBeRemoved(m_end, node);
 }
 
 static inline void boundaryTextInserted(RangeBoundaryPoint& boundary, Node* text, unsigned offset, unsigned length)
 {
-    boundary.markValid();
     if (boundary.container() != text)
         return;
+    boundary.markValid();
     unsigned boundaryOffset = boundary.offset();
     if (offset >= boundaryOffset)
         return;
     boundary.setOffset(boundaryOffset + length);
 }
 
 void Range::didInsertText(Node* text, unsigned offset, unsigned length)
 {
     DCHECK(text);
     DCHECK_EQ(text->document(), m_ownerDocument);
     boundaryTextInserted(m_start, text, offset, length);
     boundaryTextInserted(m_end, text, offset, length);
 }
 
 static inline void boundaryTextRemoved(RangeBoundaryPoint& boundary, Node* text, unsigned offset, unsigned length)
 {
-    boundary.markValid();
     if (boundary.container() != text)
         return;
+    boundary.markValid();

[yosin_UTC9, 2016/08/19 06:02:43]

Sorry, I don't understand this change.

Changing data in CharacterData node doesn't affect offset in child node of
container node.
When we move |markValid()| here and |boundaryTextInserted()|, each text data
change invalidate valid offset in container of |RangeBoundaryPoint|.

[yosin_UTC9, 2016/08/19 06:25:48]

Discussed offline. I understand this patch is correct.
Note: when container node is CharacterData, offset in RangeBoundaryPoint is
always valid. So, we don't need to update dom tree version in RBP.

     unsigned boundaryOffset = boundary.offset();
     if (offset >= boundaryOffset)
         return;
     if (offset + length >= boundaryOffset)
         boundary.setOffset(offset);
     else
         boundary.setOffset(boundaryOffset - length);
 }
 
 void Range::didRemoveText(Node* text, unsigned offset, unsigned length)
@@ skipping 170 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