Include AvailabilityMacros.h only where it is used.

Source/core/platform/graphics/mac/ComplexTextControllerCoreText.mm

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 13 matching lines @@
 
 #include "config.h"
 
 #include "core/platform/graphics/mac/ComplexTextController.h"
 
 #include "core/platform/graphics/Font.h"
 #include "core/platform/graphics/FontCache.h"
 #include "core/platform/graphics/TextRun.h"
 
 #include <ApplicationServices/ApplicationServices.h>
+#import <AvailabilityMacros.h>
 
 // Forward declare Mac SPIs.
 extern "C" {
 // Request for public API: rdar://13803619
 CTLineRef CTLineCreateWithUniCharProvider(const UniChar* (*provide)(CFIndex stringIndex, CFIndex* charCount, CFDictionaryRef* attributes, void* context), void (*dispose)(const UniChar* chars, void* context), void* context);
 }
 
 @interface WebCascadeList : NSArray {
     @private
     const WebCore::Font* _font;
@@ skipping 243 matching lines @@
             }
         }
         if (m_fallbackFonts && runFontData != m_font.primaryFont())
             m_fallbackFonts->add(fontData);
 
         m_complexTextRuns.append(ComplexTextRun::create(ctRun, runFontData, cp, stringLocation, length, runRange));
     }
 }
 
 } // namespace WebCore