Re: [xhr] statusText is underdefined

Boris Zbarsky:
>> For what it's worth, I would be reasonably happy if we had a
>> non-DOMString IDL type to indicate "raw byte sequence" strings,
>> with WebIDL defining byte-inflation as the conversion from such
>> things to JS strings...

Anne van Kesteren:
> That's an interesting idea. We could also use that for open()'s
> method argument (as doing the opposite, throw for higher than
> U+00FF, then deflate).

OK, so just like DOMString is a "raw 16 bit word sequence" string, this 
new type would be a raw 8 bit byte sequence string.  ByteString sounds 
like a good name for it.  (Although it may be inconsistent with "octet" 
being unsigned and "byte" being signed...)  Would the deflation from a 
JS String throw when it finds values > 255?