Reviewed by Dimitri Glazkov.                                            
                                                                                
        Chromium GYP build fix.                                                 
                                                                                
        When various settings were moved to webcore_prerequisites in r66364,    
        things that should have been direct_dependent_settings were not marked  
        as such. GYP 'defines', for example, make no sense on a 'none'-type     
        target such as webcore_prerequisites. It appears that it was intended   
        for these settings to be pushed to direct dependents, which would make  
        direct_dependent_settings correct.                                      
                                                                                
        Losing the ChromiumWebCoreObjC defines on the Mac, for example, caused  
        http://crbug.com/71537, which at best causes Mac console log spew, and  
        at worst may result in Chromium's copy of WebCore using system          
        definitions of certain Objective-C classes at runtime, or vice-versa.   
                                                                                
        The build now includes a postbuild step to prevent                      
        http://crbug.com/71537 from regressing again. The build will fail upon  
        regression.                                                             
                                                                                
        https://bugs.webkit.org/show_bug.cgi?id=53630                           
                                                                                
        * WebCore.gyp/WebCore.gyp: Move things in webcore_prerequisites into    
          direct_dependent_settings as needed, add the check_objc_rename        
          postbuild step.                                                       
        * WebCore.gyp/mac/check_objc_rename.sh: Added.                          
                                                                                



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@77663 268f45cc-cd09-0410-ab3c-d52691b4dbfc