resourceloader: Wrap only=script responses in "if(window.mw)"

resourceloader: Wrap only=script responses in "if(window.mw)"

We currently have a few legacy requests to the load.php end point
that bypass the ResourceLoader client by coding a request to
load.php via a "<script src>" directly. Most prominently the
request for the 'site' wiki module (aka MediaWiki:Common.js).

Remove the manual wrapping of embedded private modules as this
is now taken are of by ResourceLoader::makeModuleResponse itself.

Misc:
* Mark "jquery" and "mediawiki" as Raw modules. While the startup
  module had this already, these didn't. Without this, they'd
  get the conditional wrap – which would be a problem since mediawiki.js
  can't be conditional on 'window.mw' for that file defines that
  namespace itself.
* Strip the cache-key comment in the unit tests because the hash
  no longer matches and using the generic 'wiki' dbname was breaking
  DB queries.
* Relates to bug 63587.
* See also 05d0f6fefdcc959d which expands the reach of the non-JS
  environment to IE6 and helped expose this bug.

Change-Id: Icf6ede09b51ce212aa70ff6be4b341762ec75b4d