Replace [TreatNullAs=functionName] with [StrictTypeChecking]

Source/bindings/tests/idls/TestEventTarget.idl

Index: Source/bindings/tests/idls/TestEventTarget.idl
diff --git a/Source/bindings/tests/idls/TestEventTarget.idl b/Source/bindings/tests/idls/TestEventTarget.idl
index fbac9ed93c6495d1da511a12b9144dbb9a19dc57..4d048653ec24c64872c2cd5f24fd0f4cbc28e5f0 100644
--- a/Source/bindings/tests/idls/TestEventTarget.idl
+++ b/Source/bindings/tests/idls/TestEventTarget.idl
@@ -28,10 +28,10 @@
 
 interface TestEventTarget : EventTarget {
     getter Node item(unsigned long index);
-    setter Node (unsigned long index, Node node);
-    getter Node namedItem(DOMString name);
-    setter Node (DOMString name, [TreatUndefinedAs=anonymousNamedSetterUndefined] DOMString value);
+    [StrictTypeChecking] setter Node (unsigned long index, Node? node);
     [RaisesException] deleter boolean (unsigned long index);
+
+    getter Node namedItem(DOMString name);
+    setter Node (DOMString name, DOMString value);
     deleter boolean (DOMString name);
 };
-