Fixes flakiness in worker tests that create a Worker or SharedWorker
with a missing script URL and only attach an error handler to it.
Once the test callback returns, nothing keeps the worker rooted from
JavaScript. If GC ran before the WebWorker process reported the
script fetch failure, the Worker/WorkerAgentParent cycle could be
collected and the error event never delivered, leaving the test hung
until timeout.
Hold startup-pending WorkerAgentParents from the outside
EnvironmentSettingsObject and release that edge once the script load
succeeds, fails, or the worker closes. The worker now survives long
enough to deliver its first script-load result.
Also, allow the echo server to reflect headers by substituting it into a
provided template body, enabling them to be read programmatically as
part of a script.
Implement transfer logic for ArrayBuffer and ResizableArrayBuffer.
Change TransferDataHolder data type to Vector<u32> to reuse existing
serialization infrastructure.
Fix 5 WPT tests in `window-postmessage.window.html` that relates to
transport.
Fix `LibWeb/Text/input/Worker/Worker-postMessage-transfer.html`.
The latter is currently ignored due to flakiness, no rebaseline is
needed.
During serialization with transfer, initialize memory with known index
and initialize Serializer at position that dependent on the memory.
This is mandatory to make ArrayBuffer transport to work. It also happens
to fix 4 WPT tests, that are related to curcular references during
serialization.
The spec expects `postMessage()` to act as if it is invoked
immediately. Since `postMessage()` isn't actually invoked immediately,
keep tasks with source `PostedMessage` in the task queue, so that these
tasks are processed. Fixes a hang when `WorkerGlobalScope.close()` is
called immediately after `postMessage()`.
This aligns Workers and Window and MessagePorts to all use the same
mechanism for transferring serialized messages across realms.
It also allows transferring more message ports into a worker.
Re-enable the Worker-echo test, as none of the MessagePort tests have
themselves been flaky, and those are now using the same underlying
implementation.
