Rewrite references to "wtf/" to "platform/wtf/" in core/css and core/style.

third_party/WebKit/Source/core/css/CSSStringValue.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/css/CSSStringValue.h"
 
 #include "core/css/CSSMarkup.h"
-#include "wtf/text/WTFString.h"
+#include "platform/wtf/text/WTFString.h"
 
 namespace blink {
 
 CSSStringValue::CSSStringValue(const String& str)
     : CSSValue(kStringClass), string_(str) {}
 
 String CSSStringValue::CustomCSSText() const {
   return SerializeString(string_);
 }
 
 DEFINE_TRACE_AFTER_DISPATCH(CSSStringValue) {
   CSSValue::TraceAfterDispatch(visitor);
 }
 
 }  // namespace blink