Move files in wtf/ to platform/wtf/ (Part 3).

third_party/WebKit/Source/platform/wtf/SizeAssertions.h

 // 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.
 
 #ifndef WTF_SizeAssertions_h
 #define WTF_SizeAssertions_h
 
 namespace WTF {
 
 // The ASSERT_SIZE macro can be used to check that a given struct is the same
 // size as a class. This is useful to visualize where the space is being used in
 // a class, as well as give a useful compile error message when the size doesn't
 // match the expected value.
 template <class T, class U>
 struct assert_size {
   template <int ActualSize, int ExpectedSize>
   struct assertSizeEqual {
     static_assert(ActualSize == ExpectedSize, "Class should stay small");
     static const bool innerValue = true;
   };
   static const bool value = assertSizeEqual<sizeof(T), sizeof(U)>::innerValue;
 };
 
 }  // namespace WTF
 
 #define ASSERT_SIZE(className, sameSizeAsClassName) \
   static_assert(WTF::assert_size<className, sameSizeAsClassName>::value, "");
 
 #endif  // WTF_SizeAssertions_h