This has quite a lot of fall out. But the majority of it is just type or
UDL substitution, where the changes just fall through to other function
calls.
By changing property key storage to UTF-16, the main affected areas are:
* NativeFunction names must now be UTF-16
* Bytecode identifiers must now be UTF-16
* Module/binding names must now be UTF-16
For attributes like Element.ariaControlsElements, which are a reflection
of FrozenArray<Element>, we must return the same JS::Array object every
time the attribute is invoked - until its contents have changed. This
patch implements caching of the reflected array in accordance with the
spec.
These callbacks are evaluated synchronously via JS::Call. We do not need
to construct an expensive RootVector container just to immediately
invoke the callbacks.
Stylistically, this also helps indicate where the actual arguments start
at the call sites, by wrapping the arguments in braces.
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.
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
