REGRESSION(r171966): Custom elements in async imports don't get upgrade.

Source/core/dom/custom/CustomElementMicrotaskQueue.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:
  *
  * 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 65 matching lines @@
 #endif
 
 void CustomElementMicrotaskQueue::enqueue(PassOwnPtr<CustomElementMicrotaskStep> step)
 {
     m_queue.append(step);
 }
 
 CustomElementMicrotaskStep::Result CustomElementMicrotaskQueue::dispatch()
 {
     MicrotaskQueueInvocationScope scope(this);
-    Result result = CustomElementMicrotaskStep::Continue;
+    Vector<OwnPtr<CustomElementMicrotaskStep> > remaining;
+    Result accumulatedResult = CustomElementMicrotaskStep::ContinueWithRemoving;
 
     unsigned i;
     for (i = 0; i < m_queue.size(); ++i) {
-        result = Result(result | m_queue[i]->process());
-
+        Result result = m_queue[i]->process();
+        accumulatedResult = CustomElementMicrotaskStep::Result(result | accumulatedResult);
+        if (result & CustomElementMicrotaskStep::ShouldRemain)
+            remaining.append(m_queue[i].release());
         if (result & CustomElementMicrotaskStep::ShouldStop)
             break;
     }
 
-    bool wasStopped = i < m_queue.size();
-    if (wasStopped)
-        m_queue.remove(0, i);
-    else
-        m_queue.resize(0);
+    for (++i; i < m_queue.size(); ++i)
+        remaining.append(m_queue[i].release());
+    m_queue.swap(remaining);
 
-    return result;
+    return accumulatedResult;
 }
 
 #if !defined(NDEBUG)
 void CustomElementMicrotaskQueue::show(unsigned indent)
 {
     for (unsigned q = 0; q < m_queue.size(); ++q) {
         if (m_queue[q])
             m_queue[q]->show(indent);
         else
-            fprintf(stderr, "%*s\n", indent, "");
+            fprintf(stderr, "%*snull\n", indent, "");
     }
 }
 #endif
 
 } // namespace WebCore