Custom pseudo element types as an invalidation set feature.

Source/core/css/invalidation/StyleInvalidator.h

Index: Source/core/css/invalidation/StyleInvalidator.h
diff --git a/Source/core/css/invalidation/StyleInvalidator.h b/Source/core/css/invalidation/StyleInvalidator.h
index 77e60719b3d37201208b2128844faecb6e3e3a89..4d5171dc659ec8e9cb181e08be5e05856a5d242f 100644
--- a/Source/core/css/invalidation/StyleInvalidator.h
+++ b/Source/core/css/invalidation/StyleInvalidator.h
@@ -23,7 +23,10 @@ private:
     bool checkInvalidationSetsAgainstElement(Element&);
 
     struct RecursionData {
-        RecursionData() : m_foundInvalidationSet(false) { }
+        RecursionData()
+            : m_foundInvalidationSet(false)
+            , m_invalidateCustomPseudo(false)
+        { }
         void pushInvalidationSet(const DescendantInvalidationSet&);
         bool matchesCurrentInvalidationSets(Element&);
         bool foundInvalidationSet() { return m_foundInvalidationSet; }
@@ -31,6 +34,7 @@ private:
         Vector<AtomicString> m_invalidationClasses;
         Vector<AtomicString> m_invalidationAttributes;
         bool m_foundInvalidationSet;
+        bool m_invalidateCustomPseudo;
     };
 
     class RecursionCheckpoint {
@@ -39,6 +43,7 @@ private:
             : m_prevClassLength(data->m_invalidationClasses.size()),
             m_prevAttributeLength(data->m_invalidationAttributes.size()),
             m_prevFoundInvalidationSet(data->m_foundInvalidationSet),
+            m_prevInvalidateCustomPseudo(data->m_invalidateCustomPseudo),
             m_data(data)
         { }
         ~RecursionCheckpoint()
@@ -46,12 +51,14 @@ private:
             m_data->m_invalidationClasses.remove(m_prevClassLength, m_data->m_invalidationClasses.size() - m_prevClassLength);
             m_data->m_invalidationAttributes.remove(m_prevAttributeLength, m_data->m_invalidationAttributes.size() - m_prevAttributeLength);
             m_data->m_foundInvalidationSet = m_prevFoundInvalidationSet;
+            m_data->m_invalidateCustomPseudo = m_prevInvalidateCustomPseudo;
         }
 
     private:
         int m_prevClassLength;
         int m_prevAttributeLength;
         bool m_prevFoundInvalidationSet;
+        bool m_prevInvalidateCustomPseudo;
         RecursionData* m_data;
     };