Allocate CSSGlobalRuleSet on heap.

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

Index: third_party/WebKit/Source/core/css/CSSGlobalRuleSet.h
diff --git a/third_party/WebKit/Source/core/css/CSSGlobalRuleSet.h b/third_party/WebKit/Source/core/css/CSSGlobalRuleSet.h
index 9f46dab66beeb788bf58781de8f5ca4a8f2cd4d4..204c2a3f1d4218870f3a54673cef304082df56ed 100644
--- a/third_party/WebKit/Source/core/css/CSSGlobalRuleSet.h
+++ b/third_party/WebKit/Source/core/css/CSSGlobalRuleSet.h
@@ -21,12 +21,11 @@ class RuleSet;
 // to the ScopedStyleResolver as possible to avoid full reconstruction of these
 // rulesets on shadow tree changes. See https://crbug.com/401359
 
-class CSSGlobalRuleSet {
-  DISALLOW_NEW();
+class CSSGlobalRuleSet : public GarbageCollectedFinalized<CSSGlobalRuleSet> {
   WTF_MAKE_NONCOPYABLE(CSSGlobalRuleSet);
 
  public:
-  CSSGlobalRuleSet() {}
+  static CSSGlobalRuleSet* Create() { return new CSSGlobalRuleSet(); }
 
   void Dispose();
   void InitWatchedSelectorsRuleSet(Document&);
@@ -50,6 +49,7 @@ class CSSGlobalRuleSet {
   DECLARE_TRACE();
 
  private:
+  CSSGlobalRuleSet() {}
   // Constructed from rules in all TreeScopes including UA style and style
   // injected from extensions.
   RuleFeatureSet features_;