Don't return null from ReplaceSelectionCommand::insertAsListItems()

Source/core/editing/ReplaceSelectionCommand.cpp

 /*
  * Copyright (C) 2005, 2006, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2009, 2010, 2011 Google 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
@@ skipping 1064 matching lines @@
     Node* blockStart = enclosingBlock(insertionPos.deprecatedNode());
     if ((isListElement(refNode.get()) || (isLegacyAppleStyleSpan(refNode.get()) && isListElement(refNode->firstChild())))
         && blockStart && blockStart->renderer()->isListItem())
         refNode = insertAsListItems(toHTMLElement(refNode), blockStart, insertionPos, insertedNodes);
     else {
         insertNodeAt(refNode, insertionPos);
         insertedNodes.respondToNodeInsertion(*refNode);
     }
 
     // Mutation events (bug 22634) may have already removed the inserted content
-    if (!refNode->inDocument())
+    if (!refNode || !refNode->inDocument())

[Yuta Kitamura, 2014/04/02 09:34:49]

nit: Test for |!refNode| should probably be done right after
insertAsListItems(), since transformation into null can only
happen in the first "if" block.

[yosin_UTC9, 2014/04/03 05:01:50]

Done.

         return;
 
     bool plainTextFragment = isPlainTextMarkup(refNode.get());
 
     while (node) {
         RefPtr<Node> next = node->nextSibling();
         fragment.removeNode(node.get());
         insertNodeAfter(node, refNode);
         insertedNodes.respondToNodeInsertion(*node);
 
@@ skipping 398 matching lines @@
         removeNodeAndPruneAncestors(nodeAfterInsertionPos.get());
 
     VisibleSelection selectionAfterReplace(m_selectReplacement ? start : end, end);
 
     setEndingSelection(selectionAfterReplace);
 
     return true;
 }
 
 } // namespace WebCore