Revert of IDL: Treat undefined as missing for optional arguments with defaults

LayoutTests/fast/dom/TreeWalker/TreeWalker-basic.html

Index: LayoutTests/fast/dom/TreeWalker/TreeWalker-basic.html
diff --git a/LayoutTests/fast/dom/TreeWalker/TreeWalker-basic.html b/LayoutTests/fast/dom/TreeWalker/TreeWalker-basic.html
index 1c1411c7d00841d958030fdf1561ceabd7436cff..7c1438320e472c83262bff8dec1cc106513e5b04 100644
--- a/LayoutTests/fast/dom/TreeWalker/TreeWalker-basic.html
+++ b/LayoutTests/fast/dom/TreeWalker/TreeWalker-basic.html
@@ -35,8 +35,10 @@
     return div;
 }
 
-function check_walker(walker, root)
+test(function ()
 {
+    var root = createSampleDOM();
+    var walker = document.createTreeWalker(root);
     assert_equals(walker.toString(), '[object TreeWalker]');
     assert_equals(walker.root, root);
     assert_equals(walker.whatToShow, 0xFFFFFFFF);
@@ -52,21 +54,7 @@
     assert_idl_attribute(walker, 'nextSibling');
     assert_idl_attribute(walker, 'previousNode');
     assert_idl_attribute(walker, 'nextNode');
-}
-
-test(function ()
-{
-    var root = createSampleDOM();
-    var walker = document.createTreeWalker(root);
-    check_walker(walker, root);
-}, 'Construct a TreeWalker by document.createTreeWalker(root).');
-
-test(function ()
-{
-    var root = createSampleDOM();
-    var walker = document.createTreeWalker(root, undefined, undefined);
-    check_walker(walker, root);
-}, 'Construct a TreeWalker by document.createTreeWalker(root, undefined, undefined).');
+}, 'Construct a TreeWalker by document.createTreeWalker().');
 
 test(function ()
 {