Support invalidation sets for :host pseudo.

Source/core/css/RuleFeature.h

Index: Source/core/css/RuleFeature.h
diff --git a/Source/core/css/RuleFeature.h b/Source/core/css/RuleFeature.h
index 360ccf5f7553b75357c5a356a210dc1801b16f75..2f867f8a11bd44743a2377169d8101f1f5795799 100644
--- a/Source/core/css/RuleFeature.h
+++ b/Source/core/css/RuleFeature.h
@@ -144,6 +144,8 @@ private:
     DescendantInvalidationSet* invalidationSetForSelector(const CSSSelector&);
 
     InvalidationSetMode updateInvalidationSets(const CSSSelector&);
+    const CSSSelector* extractInvalidationSetFeatures(const CSSSelector&, Vector<AtomicString>& classes, AtomicString& id, AtomicString& tagName, Vector<AtomicString>& attributes);
+    void addFeaturesToInvalidationSets(const CSSSelector&, const Vector<AtomicString>& classes, AtomicString id, AtomicString tagName, const Vector<AtomicString>& attributes);
 
     void addClassToInvalidationSet(const AtomicString& className, Element*);