WebKit export of https://bugs.webkit.org/show_bug.cgi?id=327156

[annevk]

WebKit export from bug: Implement [SameAgentCluster] for WebCodecs objects

Implement [SameAgentCluster] for WebCodecs objects and MediaStreamTrack

whatwg/html#13055 adds the [SameAgentCluster]
extended attribute: serializing or transferring an object implementing
such an interface restricts the result to the agent cluster it came from,
deserializing it in another agent cluster throws a DataCloneError, and
serializing it for storage throws as well. This is what
w3c/webcodecs#717 needs for EncodedVideoChunk,
VideoFrame, EncodedAudioChunk, and AudioData, and what the WebCodecs
crossAgentCluster tests already expect. MediaStreamTrack and
MediaStreamTrackHandle are transferred the same way, so restrict them
too.

The bindings generator now emits isRestrictedToSameAgentCluster for
[Serializable] and [Transferable] interfaces. SerializedScriptValue maps
each serialization tag to the PlatformObjectSerializationTraits of its
interface in one place, platformObjectSerializationTraitsForTag(), which
both the exposure check and the new isTagRestrictedToSameAgentCluster()
use. When CloneSerializer writes a restricted tag it writes the agent
cluster ID after it, as JSC already does for SharedArrayBuffer, and
CloneDeserializer checks that ID before reading the object. All of these
objects already refuse to be serialized for storage, before their tag is
written.

The existing tests only cover the video types, so add tests for
AudioData, EncodedAudioChunk, MediaStreamTrack, and
MediaStreamTrackHandle.

WebKit-Bug: https://bugs.webkit.org/show_bug.cgi?id=327156

[wpt-pr-bot]

This patch has been exported from WebKit; it will be approved automatically once the downstream patch is r+.

[wpt-pr-bot]

The review process for this patch is being conducted in the WebKit project.