IDL: Further improve indexed/named property setter type checking

Source/bindings/tests/idls/core/TestInterface2.idl

Index: Source/bindings/tests/idls/core/TestInterface2.idl
diff --git a/Source/bindings/tests/idls/core/TestInterface2.idl b/Source/bindings/tests/idls/core/TestInterface2.idl
index 5a70a1aebfa77a22a38f1db5efaa20a11b1ba04d..02de68e29664a71e36300530d76c6c301c373c3d 100644
--- a/Source/bindings/tests/idls/core/TestInterface2.idl
+++ b/Source/bindings/tests/idls/core/TestInterface2.idl
@@ -46,12 +46,12 @@
 
     // Indexed property operations with an identifier
     [RaisesException] getter TestInterfaceEmpty item(unsigned long index);
-    [RaisesException] setter DOMString setItem(unsigned long index, DOMString value);
+    [RaisesException, TypeChecking=Interface] setter TestInterfaceEmpty setItem(unsigned long index, TestInterfaceEmpty value);
     [RaisesException] deleter boolean deleteItem(unsigned long index);
 
     // Named property operations with an identifier
     [RaisesException] getter TestInterfaceEmpty namedItem(DOMString name);
-    [RaisesException] setter DOMString setNamedItem(DOMString name, DOMString value);
+    [RaisesException, TypeChecking=Interface] setter TestInterfaceEmpty setNamedItem(DOMString name, TestInterfaceEmpty? value);
     [RaisesException] deleter boolean deleteNamedItem(DOMString name);
 
     stringifier DOMString stringifierMethod();