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

third_party/WebKit/Source/core/dom/CSSSelectorWatch.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 74 matching lines @@
   m_addedSelectors.clear();
   m_removedSelectors.clear();
   m_timerExpirations = 0;
 }
 
 void CSSSelectorWatch::updateSelectorMatches(
     const Vector<String>& removedSelectors,
     const Vector<String>& addedSelectors) {
   bool shouldUpdateTimer = false;
 
-  for (unsigned i = 0; i < removedSelectors.size(); ++i) {
-    const String& selector = removedSelectors[i];
+  for (const auto& selector : removedSelectors) {
     if (!m_matchingCallbackSelectors.remove(selector))
       continue;
 
     // Count reached 0.
     shouldUpdateTimer = true;
     auto it = m_addedSelectors.find(selector);
     if (it != m_addedSelectors.end())
       m_addedSelectors.remove(it);
     else
       m_removedSelectors.add(selector);
   }
 
-  for (unsigned i = 0; i < addedSelectors.size(); ++i) {
-    const String& selector = addedSelectors[i];
+  for (const auto& selector : addedSelectors) {
     HashCountedSet<String>::AddResult result =
         m_matchingCallbackSelectors.add(selector);
     if (!result.isNewEntry)
       continue;
 
     shouldUpdateTimer = true;
     auto it = m_removedSelectors.find(selector);
     if (it != m_removedSelectors.end())
       m_removedSelectors.remove(it);
     else
@@ skipping 23 matching lines @@
   }
   return true;
 }
 
 void CSSSelectorWatch::watchCSSSelectors(const Vector<String>& selectors) {
   m_watchedCallbackSelectors.clear();
 
   StylePropertySet* callbackPropertySet =
       ImmutableStylePropertySet::create(nullptr, 0, UASheetMode);
 
-  for (unsigned i = 0; i < selectors.size(); ++i) {
+  for (const auto& selector : selectors) {
     CSSSelectorList selectorList = CSSParser::parseSelector(
-        CSSParserContext(UASheetMode, nullptr), nullptr, selectors[i]);
+        CSSParserContext(UASheetMode, nullptr), nullptr, selector);
     if (!selectorList.isValid())
       continue;
 
     // Only accept Compound Selectors, since they're cheaper to match.
     if (!allCompound(selectorList))
       continue;
 
     m_watchedCallbackSelectors.append(
         StyleRule::create(std::move(selectorList), callbackPropertySet));
   }
   document().styleEngine().watchedSelectorsChanged();
 }
 
 DEFINE_TRACE(CSSSelectorWatch) {
   visitor->trace(m_watchedCallbackSelectors);
   visitor->trace(m_document);
   Supplement<Document>::trace(visitor);
 }
 
 }  // namespace blink