IDL: Add any support to IDL dictionary and use it in CustomEventInit

Source/core/events/CustomEvent.h

Index: Source/core/events/CustomEvent.h
diff --git a/Source/core/events/CustomEvent.h b/Source/core/events/CustomEvent.h
index e646ddd60a27348bce2bc7151540dd137c8fd6ea..2d5dfe1ec35654a7968b80e5cf1d03ab16de1008 100644
--- a/Source/core/events/CustomEvent.h
+++ b/Source/core/events/CustomEvent.h
@@ -27,14 +27,13 @@
 #define CustomEvent_h
 
 #include "core/CoreExport.h"
+#include "core/events/CustomEventInit.h"
 #include "core/events/Event.h"
 
 namespace blink {
 
 class SerializedScriptValue;
 
-typedef EventInit CustomEventInit;
-
 class CORE_EXPORT CustomEvent final : public Event {
     DEFINE_WRAPPERTYPEINFO();
 public:
@@ -56,11 +55,8 @@ public:
 
     SerializedScriptValue* serializedDetail() { return m_serializedDetail.get(); }
 
-    void setSerializedDetail(PassRefPtr<SerializedScriptValue> detail)
-    {
-        ASSERT(!m_serializedDetail);
-        m_serializedDetail = detail;
-    }
+    ScriptValue detail() const { return m_detail; }
+    void setDetail(ScriptValue detail) { m_detail = detail; }
 
     DECLARE_VIRTUAL_TRACE();
 
@@ -68,6 +64,7 @@ private:
     CustomEvent();
     CustomEvent(const AtomicString& type, const CustomEventInit& initializer);
 
+    ScriptValue m_detail;
     RefPtr<SerializedScriptValue> m_serializedDetail;
 };