Add previous answers to MathQuill inputs on the next tick.

[drgrice1]

This fixes openwebwork/mathquill#30. Although, I am not sure what is going on here. For some reason delaying filling in previous answers until the "next tick" (a timeout with 0 delay) fixes the problem. Probably the MathQuill math field is not fully initialized until after the mqeditor setup method completes.

I am unable to reproduce the issue using the development build of MathQuill directly via npm run serve.

[pstaabp]

Fixes the strange behavior.

[Alex-Jordan]

I checked out a copy of PG-2.19 branch and merged this branch into it. Then I ran npm ci and restarted webwork2. But I still experience the issue. I looked at the minimized mqeditor file that my browser console says is in play, and I do see that it has the setTimeout that was added here. So I think that I've set up testing correctly, but the bug described at openwebwork/mathquill#30 still happens.

[drgrice1]

Experimenting with this more I see that sometimes it happens, and sometimes it doesn't. I increased the delay before the timeout executes to a tenth of a second. I haven't been able to reproduce it with that yet. However, it might still happen anyway.

I don't really think this pull request should be merged. I think more investigation is needed to determine what is really going on. I also don't think this is particularly high priority though. I think typing \\end in text mode is an edge case that won't happen much.

[Alex-Jordan]

OK, FWIW, I pulled with the 100ms delay, and now I am not seeing the issue.

And no, this is not high priority. IIRC I was trying things that might demonstrate an insertion vulnerability and that exposed this. But no reasonable exercise would lead to a user inputting this kind of answer.

[Alex-Jordan]

Merging this for now. Maybe there's a better solution to find later.