Remove unnecessary includes from LayoutBox.h, LayoutBoxModelObject.h and LayoutObject.h

third_party/WebKit/Source/platform/graphics/CompositingReasons.h

 // Copyright 2014 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 CompositingReasons_h
 #define CompositingReasons_h
 
 #include "platform/PlatformExport.h"
 #include "wtf/Allocator.h"
-#include "wtf/MathExtras.h"
 #include <stdint.h>
 
 namespace blink {
 
 const uint64_t CompositingReasonNone                                     = 0;
 const uint64_t CompositingReasonAll                                      = ~static_cast<uint64_t>(0);
 
 // Intrinsic reasons that can be known right away by the layer
 const uint64_t CompositingReason3DTransform                              = UINT64_C(1) << 0;
 const uint64_t CompositingReasonVideo                                    = UINT64_C(1) << 1;
@@ skipping 149 matching lines @@
     const char* shortName;
     const char* description;
 };
 
 PLATFORM_EXPORT extern const CompositingReasonStringMap kCompositingReasonStringMap[];
 PLATFORM_EXPORT extern const size_t kNumberOfCompositingReasons;
 
 } // namespace blink
 
 #endif // CompositingReasons_h