Move custom element definitions into ElementRareData

Source/core/dom/ElementRareData.h

Index: Source/core/dom/ElementRareData.h
diff --git a/Source/core/dom/ElementRareData.h b/Source/core/dom/ElementRareData.h
index c3189379b3e96341787d15a303ca5f1c3a82cb71..ce0b718cca2d7636f8b50f8e6a85ab6d0728ba49 100644
--- a/Source/core/dom/ElementRareData.h
+++ b/Source/core/dom/ElementRareData.h
@@ -27,6 +27,7 @@
 #include "core/dom/NamedNodeMap.h"
 #include "core/dom/NodeRareData.h"
 #include "core/dom/PseudoElement.h"
+#include "core/dom/custom/CustomElementDefinition.h"
 #include "core/dom/shadow/ElementShadow.h"
 #include "core/html/ClassList.h"
 #include "core/html/ime/InputMethodContext.h"
@@ -147,6 +148,9 @@ public:
     bool hasPseudoElements() const;
     void clearPseudoElements();
 
+    void setCustomElementDefinition(PassRefPtr<CustomElementDefinition> definition) { m_customElementDefinition = definition; }
+    CustomElementDefinition* customElementDefinition() const { return m_customElementDefinition.get(); }
+
 private:
     short m_tabIndex;
     unsigned short m_childIndex;
@@ -186,7 +190,9 @@ private:
     RefPtr<PseudoElement> m_generatedAfter;
     RefPtr<PseudoElement> m_backdrop;
 
-    ElementRareData(RenderObject*);
+    RefPtr<CustomElementDefinition> m_customElementDefinition;
+
+    explicit ElementRareData(RenderObject*);
 };
 
 inline IntSize defaultMinimumSizeForResizing()