When we need the callback to return a promise, we can use this alternate
invoker to construct the WebIDL::Promise for us. Currently, the Streams
API will use WebIDL::invoke_callback to create a JS::Promise, and then
wrap that result in a resolved WebIDL::Promise. This results in rejected
JS::Promise instances not being propagated.
`WebIDL::invoke_callback()` now takes an `exception_behavior`
parameter, which can be set to `report` to report an exception before
returning. Setting `exception_behavior` to `rethrow` retains the
previous behavior.
We are currently returning LibJS's invalid code point message, but not
formatting it with the bad value. So we get something like:
Unhandled JavaScript exception: [TypeError] Invalid code point {},
must be an integer no less than 0 and no greater than 0x10FFFF
So not only is the error unformatted, but it's inaccurate; in this case,
the byte cannot be larger than 255.
In line with the ShadowRealm proposal changes in the WebIDL spec:
webidl#1437 and supporting changes in HTML spec.
This is required for ShadowRealms as they have no relevant settings
object on the shadow realm, so fixes a crash in the QueueingStrategy
test in this commit.
Resulting in a massive rename across almost everywhere! Alongside the
namespace change, we now have the following names:
* JS::NonnullGCPtr -> GC::Ref
* JS::GCPtr -> GC::Ptr
* JS::HeapFunction -> GC::Function
* JS::CellImpl -> GC::Cell
* JS::Handle -> GC::Root
