Created attachment 398098 [details, diff] patch removing the js extension from application/x-javascript In the mime.types file both the registered "application/javascript" and the obsolete "application/x-javascript" are listed for the js file extension. The first definition is on line 101 (application/javascript) and the second on #1163 (application/x-javascript). Because apache uses the later definition .js files served by apache have the obsolete mime type. I've attached a patch fixing this. rfc4329: http://tools.ietf.org/html/rfc4329#section-7
Resolved by app-misc/mime-types-2.1.53. See bug 762958 for further information.