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

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

Index: third_party/WebKit/Source/core/html/HTMLTextAreaElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLTextAreaElement.cpp b/third_party/WebKit/Source/core/html/HTMLTextAreaElement.cpp
index 1d9e8541a2f42b60d94b78d5b3392009bc5f9eff..aebef280f2581ce6312904903c6d090ab45d43ab 100644
--- a/third_party/WebKit/Source/core/html/HTMLTextAreaElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLTextAreaElement.cpp
@@ -480,9 +480,8 @@ void HTMLTextAreaElement::setDefaultValue(const String& defaultValue) {
     if (n->isTextNode())
       textNodes.append(n);
   }
-  size_t size = textNodes.size();
-  for (size_t i = 0; i < size; ++i)
-    removeChild(textNodes[i].get(), IGNORE_EXCEPTION);
+  for (const auto& text : textNodes)
+    removeChild(text.get(), IGNORE_EXCEPTION);
 
   // Normalize line endings.
   String value = defaultValue;