Remove the importedDocument functions from HTML imports classes.

Source/core/html/imports/LinkImport.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 46 matching lines @@
     if (m_child) {
         m_child->clearClient();
         m_child = 0;
     }
 }
 
 Document* LinkImport::importedDocument() const
 {
     if (!m_child || !m_owner || !m_owner->inDocument())
         return 0;
-    return m_child->importedDocument();
+    if (m_child->loader()->hasError())
+        return 0;
+    return m_child->document();
 }
 
 void LinkImport::process()
 {
     if (m_child)
         return;
     if (!m_owner)
         return;
     if (!shouldLoadResource())
         return;
@@ skipping 47 matching lines @@
 {
     return m_child && m_child->isDone() && !m_child->loaderHasError();
 }
 
 void LinkImport::trace(Visitor* visitor)
 {
     LinkResource::trace(visitor);
 }
 
 } // namespace WebCore