Merge 141009

Source/WebCore/rendering/RenderBlockLineLayout.cpp

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All right reserved.
  * Copyright (C) 2010 Google 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
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 1652 matching lines @@
         // Count from the end of the block backwards, to see how many hanging
         // lines we have.
         RootInlineBox* firstLineInBlock = firstRootBox();
         int numLinesHanging = 1;
         while (lineBox && lineBox != firstLineInBlock && !lineBox->isFirstAfterPageBreak()) {
             ++numLinesHanging;
             lineBox = lineBox->prevRootBox();
         }
 
         // If there were no breaks in the block, we didn't create any widows.
-        if (!lineBox->isFirstAfterPageBreak() || lineBox == firstLineInBlock)
+        if (!lineBox || !lineBox->isFirstAfterPageBreak() || lineBox == firstLineInBlock)
             return;
 
         if (numLinesHanging < style()->widows()) {
             // We have detected a widow. Now we need to work out how many
             // lines there are on the previous page, and how many we need
             // to steal.
             int numLinesNeeded = style()->widows() - numLinesHanging;
             RootInlineBox* currentFirstLineOfNewPage = lineBox;
 
             // Count the number of lines in the previous page.
@@ skipping 1624 matching lines @@
     lineGridBox->alignBoxesInBlockDirection(logicalHeight(), textBoxDataMap, verticalPositionCache);
     
     setLineGridBox(lineGridBox);
     
     // FIXME: If any of the characteristics of the box change compared to the old one, then we need to do a deep dirtying
     // (similar to what happens when the page height changes). Ideally, though, we only do this if someone is actually snapping
     // to this grid.
 }
 
 }