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

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

Index: third_party/WebKit/Source/core/dom/DOMStringList.cpp
diff --git a/third_party/WebKit/Source/core/dom/DOMStringList.cpp b/third_party/WebKit/Source/core/dom/DOMStringList.cpp
index 03a312b805d0133159d2c8f3f136c5abb78a4f7e..4350e60bb53631d3e4391f4a8daa0a02163112ca 100644
--- a/third_party/WebKit/Source/core/dom/DOMStringList.cpp
+++ b/third_party/WebKit/Source/core/dom/DOMStringList.cpp
@@ -72,9 +72,8 @@ bool DOMStringList::contains(ExecutionContext* context,
   // FIXME: Currently, all consumers of DOMStringList store fairly small lists
   // and thus an O(n) algorithm is OK.  But this may need to be optimized if
   // larger amounts of data are stored in m_strings.
-  size_t count = m_strings.size();
-  for (size_t i = 0; i < count; ++i) {
-    if (m_strings[i] == string)
+  for (const auto& item : m_strings) {
+    if (item == string)
       return true;
   }
   return false;