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

Source/platform/geometry/FloatPoint.h

Index: Source/platform/geometry/FloatPoint.h
diff --git a/Source/platform/geometry/FloatPoint.h b/Source/platform/geometry/FloatPoint.h
index 9af5be950b15235d5b29fc58d24fb42adb7add51..8734083a5b0c4b0d60a284dc59714b70996e723b 100644
--- a/Source/platform/geometry/FloatPoint.h
+++ b/Source/platform/geometry/FloatPoint.h
@@ -35,10 +35,8 @@
 #if OS(MACOSX)
 typedef struct CGPoint CGPoint;
 
-#ifdef NSGEOMETRY_TYPES_SAME_AS_CGGEOMETRY_TYPES
-typedef struct CGPoint NSPoint;
-#else
-typedef struct _NSPoint NSPoint;
+#ifdef __OBJC__
+#import <Foundation/Foundation.h>
 #endif
 #endif
 
@@ -133,7 +131,7 @@ public:
 #if OS(MACOSX)
     FloatPoint(const CGPoint&);
     operator CGPoint() const;
-#if !defined(NSGEOMETRY_TYPES_SAME_AS_CGGEOMETRY_TYPES)
+#if defined(__OBJC__) && !defined(NSGEOMETRY_TYPES_SAME_AS_CGGEOMETRY_TYPES)
     FloatPoint(const NSPoint&);
     operator NSPoint() const;
 #endif