Remove CSSCharsetRule

Source/core/css/CSSGroupingRule.cpp

 /*
  * Copyright (C) 2011 Adobe Systems Incorporated. All rights reserved.
  * Copyright (C) 2012 Apple 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:
  *
  * 1. Redistributions of source code must retain the above
  *    copyright notice, this list of conditions and the following
@@ skipping 59 matching lines @@
 
     CSSStyleSheet* styleSheet = parentStyleSheet();
     CSSParserContext context(parserContext(), UseCounter::getFrom(styleSheet));
     RefPtrWillBeRawPtr<StyleRuleBase> newRule = CSSParser::parseRule(context, styleSheet ? styleSheet->contents() : 0, ruleString);
     if (!newRule) {
         exceptionState.throwDOMException(SyntaxError, "the rule '" + ruleString + "' is invalid and cannot be parsed.");
         return 0;
     }
 
     if (newRule->isImportRule()) {
-        // FIXME: an HierarchyRequestError should also be thrown for a @charset or a nested
-        // @media rule. They are currently not getting parsed, resulting in a SyntaxError
-        // to get raised above.
+        // FIXME: an HierarchyRequestError should also be thrown for a nested @media rule. They are
+        // currently not getting parsed, resulting in a SyntaxError to get raised above.
         exceptionState.throwDOMException(HierarchyRequestError, "'@import' rules cannot be inserted inside a group rule.");
         return 0;
     }
     CSSStyleSheet::RuleMutationScope mutationScope(this);
 
     m_groupRule->wrapperInsertRule(index, newRule);
 
     m_childRuleCSSOMWrappers.insert(index, RefPtrWillBeMember<CSSRule>(nullptr));
     return index;
 }
@@ skipping 63 matching lines @@
 {
     CSSRule::trace(visitor);
 #if ENABLE(OILPAN)
     visitor->trace(m_childRuleCSSOMWrappers);
 #endif
     visitor->trace(m_groupRule);
     visitor->trace(m_ruleListCSSOMWrapper);
 }
 
 } // namespace blink