Add a first pass of a class descendant invalidator, and a containing RuleSetAnalyzer

Source/core/dom/Node.h

Index: Source/core/dom/Node.h
diff --git a/Source/core/dom/Node.h b/Source/core/dom/Node.h
index f0bff39e630c691a9a116fbbe0be649a91f07f27..eecb76ba4c7568ae4d12c53860cd986065970aa0 100644
--- a/Source/core/dom/Node.h
+++ b/Source/core/dom/Node.h
@@ -372,6 +372,13 @@ public:
     void clearChildNeedsDistributionRecalc()  { clearFlag(ChildNeedsDistributionRecalc); }
     void markAncestorsWithChildNeedsDistributionRecalc();
 
+    bool childNeedsInvalidation() const { return getFlag(ChildNeedsInvalidation); }
+    void setChildNeedsInvalidation()  { setFlag(ChildNeedsInvalidation); }
+    void clearChildNeedsInvalidation()  { clearFlag(ChildNeedsInvalidation); }
+    void markAncestorsWithChildNeedsInvalidation();
+    void setNeedsInvalidation();
+    virtual bool needsInvalidation() const;
+
     void recalcDistribution();
 
     bool shouldNotifyRendererWithIdenticalStyles() const { return getFlag(NotifyRendererWithIdenticalStyles); }
@@ -725,10 +732,12 @@ private:
         CustomElement = 1 << 27,
         CustomElementUpgraded = 1 << 28,
 
+        ChildNeedsInvalidation = 1 << 29,
+
         DefaultNodeFlags = IsParsingChildrenFinishedFlag | ChildNeedsStyleRecalcFlag | NeedsReattachStyleChange
     };
 
-    // 4 bits remaining.
+    // 2 bits remaining.
 
     bool getFlag(NodeFlags mask) const { return m_nodeFlags & mask; }
     void setFlag(bool f, NodeFlags mask) const { m_nodeFlags = (m_nodeFlags & ~mask) | (-(int32_t)f & mask); }