IDL: Add [Custom=CallEpilogue] to eliminate CG special cases

Source/core/frame/History.idl

Index: Source/core/frame/History.idl
diff --git a/Source/core/frame/History.idl b/Source/core/frame/History.idl
index ee9c0ef9efcbc3c1adb7dbc60a7d0cef571680cd..c485dc830e9a4b25bb1fbee629e8a146876e78ff 100644
--- a/Source/core/frame/History.idl
+++ b/Source/core/frame/History.idl
@@ -33,6 +33,7 @@
     [CallWith=ExecutionContext] void forward();
     [CallWith=ExecutionContext] void go([Default=Undefined] optional long distance);
 
-    [Custom, RaisesException] void pushState(any data, DOMString title, optional DOMString url);
-    [Custom, RaisesException] void replaceState(any data, DOMString title, optional DOMString url);
+    // FIXME: the title arguments below should simply be 'DOMString title'.
+    [Custom=CallEpilogue, RaisesException] void pushState(SerializedScriptValue data, [TreatUndefinedAs=NullString] DOMString? title, optional DOMString? url = null);
+    [Custom=CallEpilogue, RaisesException] void replaceState(SerializedScriptValue data, [TreatUndefinedAs=NullString] DOMString? title, optional DOMString? url = null);
 };