Remove tons of OILPAN.

sky/engine/core/css/CSSGroupingRule.cpp

Index: sky/engine/core/css/CSSGroupingRule.cpp
diff --git a/sky/engine/core/css/CSSGroupingRule.cpp b/sky/engine/core/css/CSSGroupingRule.cpp
index 88c2e90f4e9539769727cdb7804ffe08c56a45a9..a75095615665fcd7f5351acfd64ac4d4ec5a2ef7 100644
--- a/sky/engine/core/css/CSSGroupingRule.cpp
+++ b/sky/engine/core/css/CSSGroupingRule.cpp
@@ -146,14 +146,4 @@ void CSSGroupingRule::reattach(StyleRuleBase* rule)
     }
 }
 
-void CSSGroupingRule::trace(Visitor* visitor)
-{
-    CSSRule::trace(visitor);
-#if ENABLE(OILPAN)
-    visitor->trace(m_childRuleCSSOMWrappers);
-#endif
-    visitor->trace(m_groupRule);
-    visitor->trace(m_ruleListCSSOMWrapper);
-}
-
 } // namespace blink