Since we don't currently have streams, we didn't set length anywhere.
However, this is required by XHR's reliance on Fetch to get the total
number of bytes for the progress events.
Since BodyInit and Headers are tightly coupled to both Request and
Response, I chose to do all of them at once instead of introducing a
bunch of temporary conversion glue code.
Move the macro to LibJS and change it to return a throw completion
instead of a WebIDL exception. This will let us use this macro within
LibJS to handle OOM conditions.
This will make it easier to support both string types at the same time
while we convert code, and tracking down remaining uses.
One big exception is Value::to_string() in LibJS, where the name is
dictated by the ToString AO.
We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)
These classes only needed Window to get at its realm. Pass a realm
directly to construct Crypto, Encoding, HRT, IntersectionObserver,
NavigationTiming, Page, RequestIdleCallback, Selection, Streams, URL,
and XML classes.
