Load MathJax's text-chtml-full component in reviewer/previewer

[abdnh]

Loading the tex-chtml-full component in the review/preview screens results in the same TeX extensions as in the editor being loaded (where tex-svg-full is used).

Closes #1773

[dae]

I used the inspector to profile the speed difference, and it brings the ~85ms script load to ~100ms on my (fast) system, which is not ideal, but not terrible, either. Auto-loading might be a way to avoid the extra cost in the future, but this will at least move things in the right direction. Something else that might be looking into as a follow-up: the editor is using text-svg-full, and we're using text-chtml-full in the reviewer. Maybe we could switch the editor to chtml as well?

[abdnh]

the editor is using text-svg-full, and we're using text-chtml-full in the reviewer. Maybe we could switch the editor to chtml as well?

Looks like it's not very simple. One issue is that the CSS doesn't get loaded automatically.

[dae]

Thanks for looking into it. It looks like the opposite - switching the reviewer to svg - would work, but as it may possibly cause other regressions, probably best to leave things as they are for now.