This is being actively worked on by engineers from both Apple and Google. The top level bug is still:
You can see there is a fairly large bug tree associated with it. There's a lot of ongoing activity on bugs deeper in the tree.
I think perhaps the easiest way for you to keep tabs on the project is to make a saved query like:
Query: All issues
Subscription options: Notify immediately
This is available by clicking on your logged-in name in the upper right corner of ANGLE's issue tracker, and selecting "Saved queries" from the drop-down.
We don't have a firm ETA for the completion of this work but are aiming to get it done as soon as possible - definitely before the end of Q4.