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

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

 /*
  * Copyright (C) 2011 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 57 matching lines @@
                                ExceptionState& exceptionState) {
   DCHECK(node);
 
   MutationObserverOptions options = 0;
 
   if (observerInit.hasAttributeOldValue() && observerInit.attributeOldValue())
     options |= AttributeOldValue;
 
   HashSet<AtomicString> attributeFilter;
   if (observerInit.hasAttributeFilter()) {
-    const Vector<String>& sequence = observerInit.attributeFilter();
-    for (unsigned i = 0; i < sequence.size(); ++i)
-      attributeFilter.add(AtomicString(sequence[i]));
+    for (const auto& name : observerInit.attributeFilter())
+      attributeFilter.add(AtomicString(name));
     options |= AttributeFilter;
   }
 
   bool attributes = observerInit.hasAttributes() && observerInit.attributes();
   if (attributes ||
       (!observerInit.hasAttributes() && (observerInit.hasAttributeOldValue() ||
                                          observerInit.hasAttributeFilter())))
     options |= Attributes;
 
   if (observerInit.hasCharacterDataOldValue() &&
@@ skipping 129 matching lines @@
   DCHECK(!shouldBeSuspended());
 
   // Calling clearTransientRegistrations() can modify m_registrations, so it's
   // necessary to make a copy of the transient registrations before operating on
   // them.
   HeapVector<Member<MutationObserverRegistration>, 1> transientRegistrations;
   for (auto& registration : m_registrations) {
     if (registration->hasTransientRegistrations())
       transientRegistrations.append(registration);
   }
-  for (size_t i = 0; i < transientRegistrations.size(); ++i)
-    transientRegistrations[i]->clearTransientRegistrations();
+  for (const auto& registration : transientRegistrations)
+    registration->clearTransientRegistrations();
 
   if (m_records.isEmpty())
     return;
 
   MutationRecordVector records;
   records.swap(m_records);
 
   // Report the first (earliest) stack as the async cause.
   InspectorInstrumentation::AsyncTask asyncTask(
       m_callback->getExecutionContext(), records.front());
   m_callback->call(records, this);
 }
 
 void MutationObserver::resumeSuspendedObservers() {
   DCHECK(isMainThread());
   if (suspendedMutationObservers().isEmpty())
     return;
 
   MutationObserverVector suspended;
   copyToVector(suspendedMutationObservers(), suspended);
-  for (size_t i = 0; i < suspended.size(); ++i) {
-    if (!suspended[i]->shouldBeSuspended()) {
-      suspendedMutationObservers().remove(suspended[i]);
-      activateObserver(suspended[i]);
+  for (const auto& observer : suspended) {
+    if (!observer->shouldBeSuspended()) {
+      suspendedMutationObservers().remove(observer);
+      activateObserver(observer);
     }
   }
 }
 
 void MutationObserver::deliverMutations() {
   DCHECK(isMainThread());
   MutationObserverVector observers;
   copyToVector(activeMutationObservers(), observers);
   activeMutationObservers().clear();
   std::sort(observers.begin(), observers.end(), ObserverLessThan());
-  for (size_t i = 0; i < observers.size(); ++i) {
-    if (observers[i]->shouldBeSuspended())
-      suspendedMutationObservers().add(observers[i]);
+  for (const auto& observer : observers) {
+    if (observer->shouldBeSuspended())
+      suspendedMutationObservers().add(observer);
     else
-      observers[i]->deliver();
+      observer->deliver();
   }
 }
 
 DEFINE_TRACE(MutationObserver) {
   visitor->trace(m_callback);
   visitor->trace(m_records);
   visitor->trace(m_registrations);
   visitor->trace(m_callback);
 }
 
 }  // namespace blink