Register GadgetResourceLoaderModule with an array

ResourceLoader allows us to provide an object directly
solely for backwards-compatability with an alpha version
of MediaWiki, which we should not depend on, as I would
like to deprecate and remove it in core.

Change-Id: I3245cc60652373a144bd03bb47bc9c57ad9d792d
Merge "Register GadgetResourceLoaderModule with an array" into RL2