ResourceLoaderWikiModule: Check content format instead of content model

For Gadgets 2.0, we have custom content models that represent
JavaScript and CSS pages. Comparing the exact content model here
is too strict, when we really want to know if the page supports
the JavaScript or CSS formats.

Also fix a debug log comment that didn't work due to improper quoting.

Change-Id: I64e86c74173b1c88cac71483327cacdd8b9967b9