WAAbstractFileLibrary should use application/javascript for *.js, not application/x-javascript

[ThomasBrodt]

WAAbstractFileLibrary still uses application/x-javascript instead of application/javascript as mime type for files with .js extension. application/javascript is official as in RFC4329.

This is for Seaside 3.2. and the current code tab on github.
See initializing method #defaultMimeTypes

[theseion]

Thanks! Nice find.