Named getter of HTMLAllCollection etc should be nullable

Source/core/html/HTMLAllCollection.idl

Index: Source/core/html/HTMLAllCollection.idl
diff --git a/Source/core/html/HTMLAllCollection.idl b/Source/core/html/HTMLAllCollection.idl
index d56b8b6dbf560bd7fab369a2cfa1052ea5f9a1ee..d8664f691cdb421b8d42a1d1409149ddc5561b59 100644
--- a/Source/core/html/HTMLAllCollection.idl
+++ b/Source/core/html/HTMLAllCollection.idl
@@ -34,6 +34,6 @@
     readonly attribute unsigned long length;
     [ImplementedAs=item] getter Element (unsigned long index);
     [Custom] Element item([Default=Undefined] optional unsigned long index);
-    // FIXME: This should return an (HTMLCollection or Element) union.
-    [ImplementedAs=namedGetter] getter (NodeList or Element) namedItem(DOMString name);
+    // FIXME: This should return an (HTMLCollection or Element)? union.
+    [ImplementedAs=namedGetter] getter (NodeList or Element)? namedItem(DOMString name);
 };