Sibling invalidation sets

Source/core/css/invalidation/InvalidationSet.cpp

Index: Source/core/css/invalidation/InvalidationSet.cpp
diff --git a/Source/core/css/invalidation/InvalidationSet.cpp b/Source/core/css/invalidation/InvalidationSet.cpp
index 24b70d7d0a4e8ca7b749ef8f6e578ecb2461fce9..b6eb2b883d4c33903d3df218bc8bc3f071e3e25a 100644
--- a/Source/core/css/invalidation/InvalidationSet.cpp
+++ b/Source/core/css/invalidation/InvalidationSet.cpp
@@ -57,6 +57,7 @@ InvalidationSet::InvalidationSet()
     , m_customPseudoInvalid(false)
     , m_treeBoundaryCrossing(false)
     , m_insertionPointCrossing(false)
+    , m_maxDirectAdjacentSelectors(1)
 {
 }
 
@@ -99,6 +100,11 @@ bool InvalidationSet::invalidatesElement(Element& element) const
 
 void InvalidationSet::combine(const InvalidationSet& other)
 {
+    m_maxDirectAdjacentSelectors = std::max(m_maxDirectAdjacentSelectors, other.m_maxDirectAdjacentSelectors);
+
+    if (other.descendants())
+        ensureDescendantInvalidationSet().combine(*other.descendants());
+
     // No longer bother combining data structures, since the whole subtree is deemed invalid.
     if (wholeSubtreeInvalid())
         return;
@@ -169,6 +175,14 @@ WillBeHeapHashSet<AtomicString>& InvalidationSet::ensureAttributeSet()
     return *m_attributes;
 }
 
+InvalidationSet& InvalidationSet::ensureDescendantInvalidationSet()
+{
+    if (!m_descendantInvalidationSet)
+        m_descendantInvalidationSet = InvalidationSet::create();
+
+    return *m_descendantInvalidationSet;
+}
+
 void InvalidationSet::addClass(const AtomicString& className)
 {
     if (wholeSubtreeInvalid())
@@ -219,6 +233,7 @@ DEFINE_TRACE(InvalidationSet)
     visitor->trace(m_ids);
     visitor->trace(m_tagNames);
     visitor->trace(m_attributes);
+    visitor->trace(m_descendantInvalidationSet);
 #endif
 }