Avoid WTF::Vector::at() and operator[] in core/dom.

third_party/WebKit/Source/core/dom/shadow/InsertionPoint.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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 139 matching lines @@
   if (!canBeActive())
     return false;
   ShadowRoot* shadowRoot = containingShadowRoot();
   DCHECK(shadowRoot);
   if (!isHTMLShadowElement(*this) ||
       shadowRoot->descendantShadowElementCount() <= 1)
     return true;
 
   // Slow path only when there are more than one shadow elements in a shadow
   // tree. That should be a rare case.
-  const HeapVector<Member<InsertionPoint>>& insertionPoints =
-      shadowRoot->descendantInsertionPoints();
-  for (size_t i = 0; i < insertionPoints.size(); ++i) {
-    InsertionPoint* point = insertionPoints[i].get();
+  for (const auto& point : shadowRoot->descendantInsertionPoints()) {
     if (isHTMLShadowElement(*point))
       return point == this;
   }
   return true;
 }
 
 bool InsertionPoint::isShadowInsertionPoint() const {
   return isHTMLShadowElement(*this) && isActive();
 }
 
@@ skipping 122 matching lines @@
     if (!insertionPoints)
       return;
     for (size_t i = 0; i < insertionPoints->size(); ++i)
       results.append(insertionPoints->at(i).get());
     DCHECK_NE(current, insertionPoints->back().get());
     current = insertionPoints->back().get();
   }
 }
 
 }  // namespace blink