[CSS Regions] Add new regionOversetChange event

Source/core/dom/Element.h

Index: Source/core/dom/Element.h
diff --git a/Source/core/dom/Element.h b/Source/core/dom/Element.h
index 9a38dfa9868120be50f0bfa1eb3a9a533a9ec9b8..fdb54e386c4903cf38ddd5f36312cbd41199dbc9 100644
--- a/Source/core/dom/Element.h
+++ b/Source/core/dom/Element.h
@@ -31,6 +31,7 @@
 #include "core/dom/SpaceSplitString.h"
 #include "core/html/CollectionType.h"
 #include "core/platform/ScrollTypes.h"
+#include "core/rendering/RegionOversetState.h"
 
 namespace WebCore {
 
@@ -458,6 +459,9 @@ public:
 
     bool isUnresolvedCustomElement();
 
+    void setRegionOversetState(RegionOversetState);
+    RegionOversetState regionOversetState() const;
+
     AtomicString computeInheritedLanguage() const;
     Locale& locale() const;