Include AvailabilityMacros.h only where it is used.

Source/WebKit/chromium/src/mac/WebInputEventFactory.mm

 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2006-2009 Google Inc.
  *
  * 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 10 matching lines @@
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "WebInputEventFactory.h"
 
 #include <ApplicationServices/ApplicationServices.h>
+#import <AvailabilityMacros.h>
 #import <Cocoa/Cocoa.h>
 
 #include "WebInputEvent.h"
 #import "core/platform/cocoa/KeyEventCocoa.h"
 #include <wtf/ASCIICType.h>
 
 #if __MAC_OS_X_VERSION_MAX_ALLOWED == 1060
 
 // Additional Lion APIs.
 enum {
@@ skipping 907 matching lines @@
     result.globalY = temp.globalY;
 
     result.type = gestureEventTypeForEvent(event);
     result.modifiers = modifiersFromEvent(event);
     result.timeStampSeconds = [event timestamp];
 
     return result;
 }
 
 } // namespace WebKit