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

Source/bindings/core/v8/ScriptValue.h

Index: Source/bindings/core/v8/ScriptValue.h
diff --git a/Source/bindings/core/v8/ScriptValue.h b/Source/bindings/core/v8/ScriptValue.h
index 47b545371b6b7b91078fa4a2e536a2d02e73e743..010f92d62aa854f28ad1adb0efe2c4be63d40840 100644
--- a/Source/bindings/core/v8/ScriptValue.h
+++ b/Source/bindings/core/v8/ScriptValue.h
@@ -170,7 +170,12 @@ public:
     }
 
     v8::Local<v8::Value> v8Value() const;
+    // TODO(bashi): Remove v8ValueUnsafe().
     v8::Local<v8::Value> v8ValueUnsafe() const;
+    // Returns v8Value() if a given ScriptState is the same as the
+    // ScriptState which is associated with this ScriptValue. Otherwise
+    // this "clones" the v8 value and returns it.
+    v8::Local<v8::Value> v8ValueFor(ScriptState*);
 
     bool toString(String&) const;