[Mac] Rely on science, not chance, to get the proper definition of the macro

Source/platform/geometry/IntSize.h

 /*
  * Copyright (C) 2003, 2004, 2005, 2006 Apple Computer, Inc.  All rights reserved.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 14 matching lines @@
  */
 
 #ifndef IntSize_h
 #define IntSize_h
 
 #include "platform/PlatformExport.h"
 
 #if OS(MACOSX)
 typedef struct CGSize CGSize;
 
-#ifdef NSGEOMETRY_TYPES_SAME_AS_CGGEOMETRY_TYPES
-typedef struct CGSize NSSize;
-#else
-typedef struct _NSSize NSSize;
+#ifdef __OBJC__
+#import <Foundation/Foundation.h>
 #endif
 #endif
 
 namespace WebCore {
 
 class PLATFORM_EXPORT IntSize {
 public:
     IntSize() : m_width(0), m_height(0) { }
     IntSize(int width, int height) : m_width(width), m_height(height) { }
 
@@ skipping 62 matching lines @@
 
     IntSize transposedSize() const
     {
         return IntSize(m_height, m_width);
     }
 
 #if OS(MACOSX)
     explicit IntSize(const CGSize&); // don't do this implicitly since it's lossy
     operator CGSize() const;
 
-#if !defined(NSGEOMETRY_TYPES_SAME_AS_CGGEOMETRY_TYPES)
+#if defined(__OBJC__) && !defined(NSGEOMETRY_TYPES_SAME_AS_CGGEOMETRY_TYPES)
     explicit IntSize(const NSSize &); // don't do this implicitly since it's lossy
     operator NSSize() const;
 #endif
 #endif
 
 private:
     int m_width, m_height;
 };
 
 inline IntSize& operator+=(IntSize& a, const IntSize& b)
@@ skipping 31 matching lines @@
 }
 
 inline bool operator!=(const IntSize& a, const IntSize& b)
 {
     return a.width() != b.width() || a.height() != b.height();
 }
 
 } // namespace WebCore
 
 #endif // IntSize_h