This lets us take advantage of ResourceLoader's on the fly minification
rather than needing to ship a minified copy, which is problematic for
other distributions like Debian.
Because the startup module excludes raw modules, it is not possible to
load or depend upon this module, and trying to use
`mw.loader.load('html5shiv')` for example will throw an exception.
This follows-up 3a30e03645.
Change-Id: I635e224fb043c614c4918771c7c8f836575c683b
