"representing the same bytes"

[domenic]

https://xhr.spec.whatwg.org/#interface-formdata

If value is a Blob object and not a File object, then set value to a new File object, representing the same bytes, whose name attribute value is "blob".

It's not clear what other properties are copied over. Per http://w3c-test.org/XMLHttpRequest/formdata-blob.htm, at the very least type is copied over. What about isClosed? What is lastModified set to?

[annevk]

This is a problem for a number of places that take Blob objects. They don't really define how them being closed is handled.

The other internal slot problems are specific to this API probably. Maybe File API should have some primitive to convert a Blob into a File, so whenever new stuff gets added they update that operation too.

[annevk]

@mkruisselbrink are you planning on exposing low-level hooks for Blob objects and such so we don't have to go through the IDL API to define basic things like this?