Fix a bug in Range::didSplitTextNode() that may yield an invalid Range object.

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 1439 matching lines @@
     setStart(refNode->parentNode(), refNode->nodeIndex(), exceptionState);
 }
 
 void Range::checkDeleteExtract(ExceptionState& exceptionState)
 {
     if (!m_start.container()) {
         exceptionState.throwDOMException(InvalidStateError, "The range has no container. Perhaps 'detatch()' has been invoked on this object?");
         return;
     }
 
+    ASSERT(boundaryPointsValid());
+
     if (!commonAncestorContainer(exceptionState) || exceptionState.hadException())
         return;
 
     Node* pastLast = pastLastNode();
     for (Node* n = firstNode(); n != pastLast; n = NodeTraversal::next(*n)) {
         if (n->isDocumentTypeNode()) {
             exceptionState.throwDOMException(HierarchyRequestError, "The Range contains a doctype node.");
             return;
         }
     }
@@ skipping 287 matching lines @@
     ASSERT(oldNode.node().parentNode());
     ASSERT(oldNode.node().isTextNode());
     ASSERT(oldNode.node().previousSibling());
     ASSERT(oldNode.node().previousSibling()->isTextNode());
     boundaryTextNodesMerged(m_start, oldNode, offset);
     boundaryTextNodesMerged(m_end, oldNode, offset);
 }
 
 static inline void boundaryTextNodeSplit(RangeBoundaryPoint& boundary, Text& oldNode)
 {
-    if (boundary.container() != oldNode)
-        return;
+    Node* boundaryContainer = boundary.container();
     unsigned boundaryOffset = boundary.offset();
-    if (boundaryOffset <= oldNode.length())
-        return;
-    boundary.set(oldNode.nextSibling(), boundaryOffset - oldNode.length(), 0);
+    if (boundary.childBefore() == &oldNode)
+        boundary.set(boundaryContainer, boundaryOffset + 1, oldNode.nextSibling());
+    else if (boundary.container() == &oldNode && boundaryOffset > oldNode.length())
+        boundary.set(oldNode.nextSibling(), boundaryOffset - oldNode.length(), 0);
 }
 
 void Range::didSplitTextNode(Text& oldNode)
 {
     ASSERT(oldNode.document() == m_ownerDocument);
     ASSERT(oldNode.parentNode());
     ASSERT(oldNode.isTextNode());
     ASSERT(oldNode.nextSibling());
     ASSERT(oldNode.nextSibling()->isTextNode());
     boundaryTextNodeSplit(m_start, oldNode);
     boundaryTextNodeSplit(m_end, oldNode);
+    ASSERT(boundaryPointsValid());
 }
 
 void Range::expand(const String& unit, ExceptionState& exceptionState)
 {
     VisiblePosition start(startPosition());
     VisiblePosition end(endPosition());
     if (unit == "word") {
         start = startOfWord(start);
         end = endOfWord(end);
     } else if (unit == "sentence") {
@@ skipping 93 matching lines @@
 
 void showTree(const WebCore::Range* range)
 {
     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());
     }
 }
 
 #endif