Have HTMLFormElement's named getter return a RadioNodeList.

LayoutTests/fast/forms/form-radio-node-list-expected.txt

+Test RadioNodeLists returned by the HTMLFormElement named-getter.
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+PASS form1.elements.length is 10
+Check that only 'listed elements' are included in the list, if any.
+PASS radioNodeList.length is 10
+PASS radioNodeList[0] instanceof HTMLButtonElement is true
+PASS radioNodeList[1] instanceof HTMLFieldSetElement is true
+PASS radioNodeList[2] instanceof HTMLInputElement is true
+PASS radioNodeList[2].type is 'hidden'
+PASS radioNodeList[3] instanceof HTMLInputElement is true
+PASS radioNodeList[3].type is 'text'
+PASS radioNodeList[4] instanceof HTMLInputElement is true
+PASS radioNodeList[4].type is 'radio'
+PASS radioNodeList[5] instanceof HTMLKeygenElement is true
+PASS radioNodeList[6] instanceof HTMLOutputElement is true
+PASS radioNodeList[7] instanceof HTMLObjectElement is true
+PASS radioNodeList[8] instanceof HTMLSelectElement is true
+PASS radioNodeList[9] instanceof HTMLTextAreaElement is true
+
+Check that if no 'listed elements' match by name, img elements are picked instead.
+PASS radioNodeList.length is 2
+PASS radioNodeList[0] instanceof HTMLImageElement is true
+PASS radioNodeList[1] instanceof HTMLImageElement is true
+PASS radioNodeList.length is 2
+PASS radioNodeList[0] instanceof HTMLImageElement is true
+PASS radioNodeList[1] instanceof HTMLImageElement is true
+PASS radioNodeList.length is 3
+PASS radioNodeList[0] instanceof HTMLImageElement is true
+PASS radioNodeList[1] instanceof HTMLImageElement is true
+PASS radioNodeList[2] instanceof HTMLImageElement is true
+PASS successfullyParsed is true
+
+TEST COMPLETE
+ 
+            
+                 
+