Check for null StringImpl in blockIsRowOfLinks.

Source/core/rendering/TextAutosizer.cpp

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 176 matching lines @@
     //     have the same specified font size.
     //  3. It should not contain <br> elements.
     //  4. It should contain only inline elements unless they are containers,
     //     children of link elements or children of sub-containers.
     int linkCount = 0;
     RenderObject* renderer = block->firstChild();
     float matchingFontSize = -1;
 
     while (renderer) {
         if (!isPotentialClusterRoot(renderer)) {
-            if (renderer->isText() && toRenderText(renderer)->text().impl()->stripWhiteSpace()->length() > 3)
+            if (renderer->isText() && toRenderText(renderer)->text().stripWhiteSpace().length() > 3)
                 return false;
             if (!renderer->isInline() || renderer->isBR())
                 return false;
         }
         if (renderer->style()->isLink()) {
             linkCount++;
             if (matchingFontSize < 0)
                 matchingFontSize = renderer->style()->specifiedFontSize();
             else if (matchingFontSize != renderer->style()->specifiedFontSize())
                 return false;
@@ skipping 955 matching lines @@
     }
     return computedSize;
 }
 
 void TextAutosizer::trace(Visitor* visitor)
 {
     visitor->trace(m_document);
 }
 
 } // namespace blink