*** DO NOT LAND *** Attempt to understand Regions complexity

Source/core/css/CSSPropertySourceData.h

 /*
  * Copyright (c) 2010 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 76 matching lines @@
 struct CSSRuleSourceData : public RefCounted<CSSRuleSourceData> {
     enum Type {
         UNKNOWN_RULE,
         STYLE_RULE,
         CHARSET_RULE,
         IMPORT_RULE,
         MEDIA_RULE,
         FONT_FACE_RULE,
         PAGE_RULE,
         KEYFRAMES_RULE,
-        REGION_RULE,
         VIEWPORT_RULE,
         SUPPORTS_RULE,
         FILTER_RULE
     };
 
     static PassRefPtr<CSSRuleSourceData> create(Type type)
     {
         return adoptRef(new CSSRuleSourceData(type));
     }
 
@@ skipping 23 matching lines @@
     // Only for CSSStyleRules, CSSFontFaceRules, and CSSPageRules.
     RefPtr<CSSStyleSourceData> styleSourceData;
 
     // Only for CSSMediaRules.
     RuleSourceDataList childRules;
 };
 
 } // namespace WebCore
 
 #endif // CSSPropertySourceData_h