Currently, these forward declarations make widl add IHTMLDocument2's `URL`
symbol before the other, lowercased, `url` symbols to the type library
(from IHTMLMetaElement, IDOMStorageEvent, etc). Since the typelib symbols
are case insensitive, `URL` ends up stored instead of `url`, which doesn't
match native.
Signed-off-by: Gabriel Ivăncescu <gabrielopcode@gmail.com>