Fix crash when trying to iterate over words in an inline text box of length zero.

Source/core/rendering/AbstractInlineTextBox.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 114 matching lines @@
 }
 
 void AbstractInlineTextBox::wordBoundaries(Vector<WordBoundaries>& words) const
 {
     if (!m_inlineTextBox)
         return;
 
     String text = this->text();
     int len = text.length();
     TextBreakIterator* iterator = wordBreakIterator(text, 0, len);
+
+    // FIXME: When http://crbug.com/411764 is fixed, replace this with an ASSERT.
+    if (!iterator)
+        return;
+
     int pos = iterator->first();
     while (pos >= 0 && pos < len) {
         int next = iterator->next();
         if (isWordTextBreak(iterator))
             words.append(WordBoundaries(pos, next));
         pos = next;
     }
 }
 
 String AbstractInlineTextBox::text() const
@@ skipping 10 matching lines @@
         return plainText(range.get(), TextIteratorIgnoresStyleVisibility);
     }
 
     String result = m_renderText->text().substring(start, len).simplifyWhiteSpace(WTF::DoNotStripWhiteSpace);
     if (m_inlineTextBox->nextTextBox() && m_inlineTextBox->nextTextBox()->start() > m_inlineTextBox->end() && result.length() && !result.right(1).containsOnlyWhitespace())
         return result + " ";
     return result;
 }
 
 } // namespace blink