The spec for filtered responses states:
Unless stated otherwise a filtered response’s associated concepts
(such as its body) refer to the associated concepts of its internal
response.
This includes setting its associated concepts. In particular, when the
filtered response's body is set upon fetching a request with integrity
metadata, we must set the internal response's body instead.
Further restrictions that apply to filtered response subclasses (such as
opaque filtered responses having a status code of 0) are already
implemented.
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
Now that the heap has no knowledge about a JavaScript realm and is
purely for managing the memory of the heap, it does not make sense
to name this function to say that it is a non-realm variant.
