Rewrite references to "wtf/" to "platform/wtf/" in core/layout.

third_party/WebKit/Source/core/layout/ng/geometry/ng_margin_strut.cc

 // Copyright 2016 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/layout/ng/geometry/ng_margin_strut.h"
 
-#include "wtf/text/WTFString.h"
+#include "platform/wtf/text/WTFString.h"
 
 namespace blink {
 
 LayoutUnit NGMarginStrut::Sum() const {
   return margin + negative_margin;
 }
 
 bool NGMarginStrut::operator==(const NGMarginStrut& other) const {
   return margin == other.margin && negative_margin == other.negative_margin;
 }
 
 void NGMarginStrut::Append(const LayoutUnit& value) {
   if (value < 0) {
     negative_margin = std::min(value, negative_margin);
   } else {
     margin = std::max(value, margin);
   }
 }
 
 String NGMarginStrut::ToString() const {
   return String::Format("%d %d", margin.ToInt(), negative_margin.ToInt());
 }
 
 std::ostream& operator<<(std::ostream& stream, const NGMarginStrut& value) {
   return stream << value.ToString();
 }
 
 }  // namespace blink