Cache results from respondsToSelector.

Source/core/core.gyp

 #
 # Copyright (C) 2009 Google 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:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
@@ skipping 474 matching lines @@
               'WebScrollbarPainterDelegate=ChromiumWebCoreObjCWebScrollbarPainterDelegate',
               'WebScrollbarPartAnimation=ChromiumWebCoreObjCWebScrollbarPartAnimation',
             ],
             'postbuilds': [
               {
                 # This step ensures that any Objective-C names that aren't
                 # redefined to be "safe" above will cause a build failure.
                 'postbuild_name': 'Check Objective-C Rename',
                 'variables': {
                   'class_whitelist_regex':
-                      'ChromiumWebCoreObjC|TCMVisibleView|RTCMFlippedView',
+                      'ChromiumWebCoreObjC|TCMVisibleView|RTCMFlippedView|ScrollerStyleObserver',
                   'category_whitelist_regex':
                       'TCMInterposing|ScrollAnimatorChromiumMacExt|WebCoreTheme',
                 },
                 'action': [
                   'scripts/check_objc_rename.sh',
                   '<(class_whitelist_regex)',
                   '<(category_whitelist_regex)',
                 ],
               },
             ],
@@ skipping 585 matching lines @@
         '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/V8LayerRect.h',
         '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/V8LayerRectList.cpp',
         '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/V8LayerRectList.h',
       ],
       'sources/': [
         ['exclude', 'testing/js'],
       ],
     },
   ],  # targets
 }