Our structured serialization implementation had its own bespoke encoder
and decoder to serialize JS values. It also used a u32 buffer under the
hood, which made using its structures a bit awkward. We had previously
worked around its data structures in transferable streams, which nested
transfers of MessagePort instances. We basically had to add hooks into
the MessagePort to route to the correct transfer receiving steps, and
we could not invoke the correct AOs directly as the spec dictates.
We now use IPC mechanics to encode and decode data. This works because,
although we are encoding JS values, we are only ultimately encoding
primitive and basic AK types. The resulting data structures actually
enforce that we implement transferable streams exactly as the spec is
worded (I had planned to do that in a separate commit, but the fallout
of this patch actually required that change).
We currently store Web::Fetch::Infrastructure::Response objects in the
HTTP cache. They are associated with their original realm, but when we
use a cached response, we clone it into the target realm. For example,
two <iframe> objects loading the same HTML will be in different realms.
When we clone the response, we must use the target realm throughout the
entire cloning process. We neglected to do this for the cloned response
body stream, which is cloned via teeing. The result was the the stream
for the "cloned" response was created in the original realm, causing
issues down the line when reading from that stream tried to handle read
promises on behalf of the original realm. There are protections in place
to prevent this from happening, and the cached response read would never
complete.
This mistakenly implemented the 'piped to' operation on ReadableStream.
No functional difference as the caller was doing the extra work already
of 'piped through' vs 'piped to'.
As far as I can tell there is no change in WPT from this implementation.
But these steps should be more effecient than using the non BYOB steps
as we can make direct use of the provided buffer to the byte stream.
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
