source map files probably should be application/json

[jokeyrhyme]

http://stackoverflow.com/questions/19911929/what-mime-type-should-i-use-for-source-map-files
http://stackoverflow.com/questions/18809567/what-is-the-correct-mime-type-for-min-map-javascript-source-files

While none of the development tools actually care, application/json has the advantage of being previewed in most development tools.

[jokeyrhyme]

We've seen .min.map, .js.map and .src.map extensions.