Make ElementShadow::oldestShadowRoot() return a reference

third_party/WebKit/Source/core/dom/shadow/ElementShadow.cpp

 /*
  * Copyright (C) 2012 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.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 314 matching lines @@
         result.storedValue->value = new DestinationInsertionPoints;
     result.storedValue->value->append(insertionPoint);
 }
 
 const SelectRuleFeatureSet& ElementShadow::ensureSelectFeatureSet()
 {
     if (!m_needsSelectFeatureSet)
         return m_selectFeatures;
 
     m_selectFeatures.clear();
-    for (ShadowRoot* root = oldestShadowRoot(); root; root = root->youngerShadowRoot())
+    for (ShadowRoot* root = &oldestShadowRoot(); root; root = root->youngerShadowRoot())
         collectSelectFeatureSetFrom(*root);
     m_needsSelectFeatureSet = false;
     return m_selectFeatures;
 }
 
 void ElementShadow::collectSelectFeatureSetFrom(ShadowRoot& root)
 {
     if (!root.containsShadowRoots() && !root.containsContentElements())
         return;
 
@@ skipping 31 matching lines @@
     visitor->trace(m_selectFeatures);
     visitor->trace(m_shadowRoot);
 }
 
 DEFINE_TRACE_WRAPPERS(ElementShadow)
 {
     visitor->traceWrappers(m_shadowRoot);
 }
 
 } // namespace blink