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

third_party/WebKit/Source/core/dom/SpaceSplitString.h

Index: third_party/WebKit/Source/core/dom/SpaceSplitString.h
diff --git a/third_party/WebKit/Source/core/dom/SpaceSplitString.h b/third_party/WebKit/Source/core/dom/SpaceSplitString.h
index e9a0a97567e7e078f30c76868f69753d44bc9f55..cb52132ae773ed192c48247fdbd08641702a919d 100644
--- a/third_party/WebKit/Source/core/dom/SpaceSplitString.h
+++ b/third_party/WebKit/Source/core/dom/SpaceSplitString.h
@@ -67,9 +67,8 @@ class SpaceSplitString {
     ~Data();
 
     bool contains(const AtomicString& string) {
-      size_t size = m_vector.size();
-      for (size_t i = 0; i < size; ++i) {
-        if (m_vector[i] == string)
+      for (const auto& item : m_vector) {
+        if (item == string)
           return true;
       }
       return false;