There's been some discussion on the public-webapps listserv to introduce a File constructor, alongside the existing Blob constructor:
Use cases covered in these discussions are:
1. Better unit tests
2. Binding Blob to name. Blobs already have a type, along with a content length. Adding the ability to name a Blob works with server applications better, especially along with FormData
Of these, 1. above is either a weak or poorly understood use case. 2. Might be workable, but within the Blob constructor.
Done -- see http://dev.w3.org/2006/webapi/FileAPI/#file