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

third_party/WebKit/Source/core/layout/ng/geometry/ng_physical_size.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_physical_size.h"
 
 #include "core/layout/ng/geometry/ng_logical_size.h"
-#include "wtf/text/WTFString.h"
+#include "platform/wtf/text/WTFString.h"
 
 namespace blink {
 
 bool NGPhysicalSize::operator==(const NGPhysicalSize& other) const {
   return std::tie(other.width, other.height) == std::tie(width, height);
 }
 
 NGLogicalSize NGPhysicalSize::ConvertToLogical(NGWritingMode mode) const {
   return mode == kHorizontalTopBottom ? NGLogicalSize(width, height)
                                       : NGLogicalSize(height, width);
 }
 
 String NGPhysicalSize::ToString() const {
   return String::Format("%dx%d", width.ToInt(), height.ToInt());
 }
 
 std::ostream& operator<<(std::ostream& os, const NGPhysicalSize& value) {
   return os << value.ToString();
 }
 
 }  // namespace blink