Currently to be able to use direct tasks, which ar similar to the JS Promise microtasks, we need an AbstractThread and its tail dispatcher.

This is an implementation detail that doesn't have to be.

So the plan is to split direct task dispatching from the tail dispatcher and abstract thread.

We will do so with a new nsIDirectTaskDispatcher task.

nsThread and TaskQueue will then implement it.

For this to be usable with MozPromise (which may require direct task dispatching), we need bug 1637500 to be resolved.

DirectTask dispatching will now be directly handled by nsThread.

DirectTask dispatching will now be directly handled by nsThread.

Depends on D79085

DirectTask dispatching will now be directly handled by nsThread.

Depends on D79086

DirectTask dispatching will now be directly handled by nsThread.

Depends on D79087

DirectTask dispatching will now be directly handled by nsThread.

Depends on D79088

DirectTask dispatching will now be directly handled by nsThread.

Depends on D79089

DirectTask dispatching will now be directly handled by nsThread.

Depends on D79090

We will use it later for implementing direct task dispatching where required.

Depends on D79091

We extract the dealing of direct tasks from the TailDispatcher object and move into to the existing nsThread and TaskQueue classes.
TaskQueue is made to work with do_QueryInterface.

We continue accessing the direct tasks dispatcher via the TailDispatcher for now, which itself will forward the dealing of such tasks to the underlying thread.

Depends on D79092

Depends on D79093

It will simply forward the interface to the main thread.
This is the final step required to remove AbstractThread support here.

Depends on D79094

This prevent being able to assert in the AutoTaskDispatcher that we are using it from the right thread/taskqueue as the SimpleTaskQueue object isn't thread-safe.

We want to assert that all nsIDirectTaskDispatcher methods are only ever accessed on the underlying thread. To do so require that the scope of AutoTaskDispatcher to terminate prior the AutoTaskGuard one.

Depends on D79095

Depends on D79096

Depends on D79095

https://hg.mozilla.org/mozilla-central/rev/50563df7052a
https://hg.mozilla.org/mozilla-central/rev/70208fbe3755
https://hg.mozilla.org/mozilla-central/rev/12725e7040d6
https://hg.mozilla.org/mozilla-central/rev/28097e44c058
https://hg.mozilla.org/mozilla-central/rev/62b9fb746823
https://hg.mozilla.org/mozilla-central/rev/4dbb4af6a2ab
https://hg.mozilla.org/mozilla-central/rev/81a565d1fd64
https://hg.mozilla.org/mozilla-central/rev/f6fc16f49976
https://hg.mozilla.org/mozilla-central/rev/faa8e3461f33
https://hg.mozilla.org/mozilla-central/rev/a0fe9db3ab56
https://hg.mozilla.org/mozilla-central/rev/b7ed3455ea43
https://hg.mozilla.org/mozilla-central/rev/0888e8f9b191
https://hg.mozilla.org/mozilla-central/rev/d985d78962c7
https://hg.mozilla.org/mozilla-central/rev/86419b2114e5