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

third_party/WebKit/Source/core/html/HTMLMediaElement.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 1212 matching lines @@
   return WebMediaPlayer::LoadTypeURL;
 }
 
 bool HTMLMediaElement::textTracksAreReady() const {
   // 4.8.10.12.1 Text track model
   // ...
   // The text tracks of a media element are ready if all the text tracks whose
   // mode was not in the disabled state when the element's resource selection
   // algorithm last started now have a text track readiness state of loaded or
   // failed to load.
-  for (unsigned i = 0; i < m_textTracksWhenResourceSelectionBegan.size(); ++i) {
-    if (m_textTracksWhenResourceSelectionBegan[i]->getReadinessState() ==
-            TextTrack::Loading ||
-        m_textTracksWhenResourceSelectionBegan[i]->getReadinessState() ==
-            TextTrack::NotLoaded)
+  for (const auto& textTrack : m_textTracksWhenResourceSelectionBegan) {
+    if (textTrack->getReadinessState() == TextTrack::Loading ||
+        textTrack->getReadinessState() == TextTrack::NotLoaded)
       return false;
   }
 
   return true;
 }
 
 void HTMLMediaElement::textTrackReadyStateChanged(TextTrack* track) {
   if (webMediaPlayer() &&
       m_textTracksWhenResourceSelectionBegan.contains(track)) {
     if (track->getReadinessState() != TextTrack::Loading)
@@ skipping 2807 matching lines @@
       kMostlyFillViewportBecomeStableSeconds, BLINK_FROM_HERE);
 }
 
 void HTMLMediaElement::viewportFillDebouncerTimerFired(TimerBase*) {
   m_mostlyFillingViewport = true;
   if (m_webMediaPlayer)
     m_webMediaPlayer->becameDominantVisibleContent(m_mostlyFillingViewport);
 }
 
 }  // namespace blink