Validation/Invalidation coordination problem with TreeSitterClient and TextSystemStyler

[mattmassicotte]

There is currently no good way to coordinate changes between TreeSitterClient and a TextSystemStyler.

On change both a client and the styler need to be updated.

• If you update the styler first, it will end up trying to validate synchronously (ok), but the client hasn't yet been updated so that fails.
• If you update the client first, it will produce invalidations that will result in the styler performing work without yet processing the change.

This coordination problem existed with Neon 0.6 as well. The solution was either to wait for the next runloop turn to apply styling (easy, could result in styling flicker), or to use precise NSTextStorage/NSLayoutManger event hooks that aren't easy to set up (without TSYTextStorage from TextStory).

[mattmassicotte]

Ok, this now has better behavior with 64c168b. I'm not sure this is the final solution, but it's something.

[mattmassicotte]

I'm going to leave this issue open until I have proved to myself that this can be used successfully to guarantee synchronous styling on content change.