[FileAPI] File.mediaType

[Anne van Kesteren]

This should be a bit more exact as to how the mediaType is returned. I  
would prefer ASCII-lowercase. Returning "application/octet-stream" rather  
than null also seems better if the type is not known. That way you do not  
have to type check. Other parts of the platform also handle  
"application/octet-stream" as unknown.

Also, maybe we should just call this type? File.type seems unambiguous  
enough.


--
Anne van Kesteren
http://annevankesteren.nl/