Oilpan: promptly dispose style resolvers upon clearing.

third_party/WebKit/Source/core/css/RuleSet.h

Index: third_party/WebKit/Source/core/css/RuleSet.h
diff --git a/third_party/WebKit/Source/core/css/RuleSet.h b/third_party/WebKit/Source/core/css/RuleSet.h
index 8e5de804518b85e510e7cc64bcb24c92705592c1..def79145232e53f8904181dd7e3a24dbf0b01859 100644
--- a/third_party/WebKit/Source/core/css/RuleSet.h
+++ b/third_party/WebKit/Source/core/css/RuleSet.h
@@ -119,11 +119,16 @@ struct SameSizeAsRuleData {
 
 static_assert(sizeof(RuleData) == sizeof(SameSizeAsRuleData), "RuleData should stay small");
 
-class CORE_EXPORT RuleSet : public NoBaseWillBeGarbageCollectedFinalized<RuleSet> {
+class CORE_EXPORT RuleSet final : public NoBaseWillBeGarbageCollectedFinalized<RuleSet> {
     WTF_MAKE_NONCOPYABLE(RuleSet);
     WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED(RuleSet);
 public:
-    static PassOwnPtrWillBeRawPtr<RuleSet> create() { return adoptPtrWillBeNoop(new RuleSet); }
+    static PassOwnPtrWillBeRawPtr<RuleSet> create()
+    {
+        return adoptPtrWillBeNoop(new RuleSet);
+    }
+    ~RuleSet();
+    void dispose();
 
     void addRulesFromSheet(StyleSheetContents*, const MediaQueryEvaluator&, AddRuleFlags = RuleHasNoSpecialState);
     void addStyleRule(StyleRule*, AddRuleFlags);