Include AvailabilityMacros.h only where it is used.

Tools/DumpRenderTree/chromium/LayoutTestHelper.mm

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2012 Apple Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 11 matching lines @@
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR 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.
  */
 
+#import <AvailabilityMacros.h>
 #import <AppKit/AppKit.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 
 // This is a simple helper app that changes the color sync profile to the
 // generic profile and back when done.  This program is managed by the layout
 // test script, so it can do the job for multiple DumpRenderTree while they are
 // running layout tests.
 
@@ skipping 162 matching lines @@
 
     // Wait for any key (or signal)
     getchar();
 
     // Restore the profile
     restoreUserColorProfile();
 
     [pool release];
     return 0;
 }