Revert of Revert of Split out CSSParser public API

Source/core/css/CSSGroupingRule.cpp

Index: Source/core/css/CSSGroupingRule.cpp
diff --git a/Source/core/css/CSSGroupingRule.cpp b/Source/core/css/CSSGroupingRule.cpp
index e7ee1927213f0ff8c05d91af20ec010c13268c1d..b19fe9a16380cdbea5c65fa7d5c16992365d09dd 100644
--- a/Source/core/css/CSSGroupingRule.cpp
+++ b/Source/core/css/CSSGroupingRule.cpp
@@ -32,9 +32,9 @@
 #include "core/css/CSSGroupingRule.h"
 
 #include "bindings/core/v8/ExceptionState.h"
-#include "core/css/parser/BisonCSSParser.h"
 #include "core/css/CSSRuleList.h"
 #include "core/css/CSSStyleSheet.h"
+#include "core/css/parser/CSSParser.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/frame/UseCounter.h"
 #include "wtf/text/StringBuilder.h"
@@ -70,8 +70,7 @@
 
     CSSStyleSheet* styleSheet = parentStyleSheet();
     CSSParserContext context(parserContext(), UseCounter::getFrom(styleSheet));
-    BisonCSSParser parser(context);
-    RefPtrWillBeRawPtr<StyleRuleBase> newRule = parser.parseRule(styleSheet ? styleSheet->contents() : 0, ruleString);
+    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;