Make ElementShadow::oldestShadowRoot() return a reference

third_party/WebKit/Source/core/dom/SelectorQuery.cpp

 /*
  * Copyright (C) 2011, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Samsung Electronics. 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.
@@ skipping 375 matching lines @@
 
 // FIXME: Move the following helper functions, authorShadowRootOf, firstWithinTraversingShadowTree,
 // nextTraversingShadowTree to the best place, e.g. NodeTraversal.
 static ShadowRoot* authorShadowRootOf(const ContainerNode& node)
 {
     if (!node.isElementNode() || !isShadowHost(&node))
         return nullptr;
 
     ElementShadow* shadow = toElement(node).shadow();
     DCHECK(shadow);
-    for (ShadowRoot* shadowRoot = shadow->oldestShadowRoot(); shadowRoot; shadowRoot = shadowRoot->youngerShadowRoot()) {
+    for (ShadowRoot* shadowRoot = &shadow->oldestShadowRoot(); shadowRoot; shadowRoot = shadowRoot->youngerShadowRoot()) {
         if (shadowRoot->type() == ShadowRootType::V0 || shadowRoot->type() == ShadowRootType::Open)
             return shadowRoot;
     }
     return nullptr;
 }
 
 static ContainerNode* firstWithinTraversingShadowTree(const ContainerNode& rootNode)
 {
     if (ShadowRoot* shadowRoot = authorShadowRootOf(rootNode))
         return shadowRoot;
@@ skipping 179 matching lines @@
 
     return m_entries.add(selectors, SelectorQuery::adopt(std::move(selectorList))).storedValue->value.get();
 }
 
 void SelectorQueryCache::invalidate()
 {
     m_entries.clear();
 }
 
 } // namespace blink