Custom pseudo element types as an invalidation set feature.

Source/core/css/invalidation/DescendantInvalidationSet.h

Index: Source/core/css/invalidation/DescendantInvalidationSet.h
diff --git a/Source/core/css/invalidation/DescendantInvalidationSet.h b/Source/core/css/invalidation/DescendantInvalidationSet.h
index 93c18e6baefecd80c221924bc36ef248a00c865c..92646fcb680ace3b847b6ac98efe94dd5dc1cfae 100644
--- a/Source/core/css/invalidation/DescendantInvalidationSet.h
+++ b/Source/core/css/invalidation/DescendantInvalidationSet.h
@@ -66,6 +66,10 @@ public:
 
     void setWholeSubtreeInvalid();
     bool wholeSubtreeInvalid() const { return m_allDescendantsMightBeInvalid; }
+
+    void setCustomPseudoInvalid() { m_customPseudoInvalid = true; }
+    bool customPseudoInvalid() const { return m_customPseudoInvalid; }
+
 private:
     DescendantInvalidationSet();
 
@@ -77,6 +81,9 @@ private:
     // If true, all descendants might be invalidated, so a full subtree recalc is required.
     bool m_allDescendantsMightBeInvalid;
 
+    // If true, all descendants which are custom pseudo elements must be invalidated.
+    bool m_customPseudoInvalid;
+
     // FIXME: optimize this if it becomes a memory issue.
     OwnPtr<HashSet<AtomicString> > m_classes;
     OwnPtr<HashSet<AtomicString> > m_ids;