Sync the HTMLCollection interfaces with the specs

Source/core/html/HTMLFormControlsCollection.idl

Index: Source/core/html/HTMLFormControlsCollection.idl
diff --git a/Source/core/html/HTMLFormControlsCollection.idl b/Source/core/html/HTMLFormControlsCollection.idl
index 68fd4b7c52f7605cad8939aab8a2b0b7b4c24978..90ca0915aada5d7f227d4a18c43d6bc01274b825 100644
--- a/Source/core/html/HTMLFormControlsCollection.idl
+++ b/Source/core/html/HTMLFormControlsCollection.idl
@@ -19,10 +19,15 @@
  * Boston, MA 02110-1301, USA.
  */
 
+// https://html.spec.whatwg.org/#the-htmlformcontrolscollection-interface
+
 [
     DependentLifetime,
     SetWrapperReferenceFrom=ownerNode,
 ] interface HTMLFormControlsCollection : HTMLCollection {
-    [ImplementedAs=item] getter Node (unsigned long index);
+    // inherits length and item()
+    // FIXME: namedItem() should be a legacycaller. crbug.com/465009
     [ImplementedAs=namedGetter] getter (RadioNodeList or Element)? namedItem(DOMString name); // shadows inherited namedItem()
+    // FIXME: This getter is not in the spec.
+    [ImplementedAs=item] getter Node (unsigned long index);
 };