EditPage: Optimise loading of mediawiki.toolbar module

EditPage: Optimise loading of mediawiki.toolbar module

Follows-up b3830611c4.

Unlike getEditToolbar(), which only runs if the user preference
is enabled, the loading of mediawiki.action.edit is unconditional.

As mediawiki.toolbar has already been separated from mediawiki.action.edit,
it's easy to load it conditionally instead of via a dependency
(mediawiki.action.edit doesn't depend on it for anything else).

Also:
* Remove odd 'false' values passed to User::getOption(). These
  options are part of MediaWiki core and always exist. The default
  value 'false' was ignored.
* Remove redundant closure. The domready callback already provides
  a closure and 'mw' is not used here (similar to jquery.mw-jump).

Change-Id: Ib2f4633b328cf8090df43b8d286cfcd77f95c5ea