Custom pseudo element types as an invalidation set feature.

Source/core/css/invalidation/DescendantInvalidationSet.cpp

Index: Source/core/css/invalidation/DescendantInvalidationSet.cpp
diff --git a/Source/core/css/invalidation/DescendantInvalidationSet.cpp b/Source/core/css/invalidation/DescendantInvalidationSet.cpp
index f7c802db3c68a9d7351f966abd725aac137d58d2..18bd5b630b493a8274db71cdfbbba6579fc8b562 100644
--- a/Source/core/css/invalidation/DescendantInvalidationSet.cpp
+++ b/Source/core/css/invalidation/DescendantInvalidationSet.cpp
@@ -38,6 +38,7 @@ namespace WebCore {
 
 DescendantInvalidationSet::DescendantInvalidationSet()
     : m_allDescendantsMightBeInvalid(false)
+    , m_customPseudoInvalid(false)
 {
 }
 
@@ -52,6 +53,9 @@ void DescendantInvalidationSet::combine(const DescendantInvalidationSet& other)
         return;
     }
 
+    if (other.customPseudoInvalid())
+        setCustomPseudoInvalid();
+
     if (other.m_classes) {
         HashSet<AtomicString>::const_iterator end = other.m_classes->end();
         for (HashSet<AtomicString>::const_iterator it = other.m_classes->begin(); it != end; ++it)