[encoding] Add do not flush flag to encode API, accept DOMString (#14)

_Filing this for tracking purposes - we may decide to immediately close. I thought we had an issue on this already._

The decode API has a **do not flush flag** (spelled `stream`) used when partial byte sequences might be encountered.

But the encode API does not. It consumes USVStrings, which implies that the content to be encoded will always be complete strings. This means the case where partial UTF-16 data might be seen is not supported; a string split in between UTF-16 surrogates would be corrupted (c/o the IDL binding for USVString, nothing explicit in the API definition).

We had support for this in earlier iterations of the API, but moved to USVStrings and thus a `stream` option was a no-op and dropped.

I don't have a use case for this, but if anyone does we could reconsider. cc: @hsivonen since he is actively poking at the spec and should be aware of this limitation. 


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Reply to this email directly or view it on GitHub:
https://github.com/whatwg/encoding/issues/14