Can't copy-paste mathjax from browser to "add note"

Running on 862dfd639de44adb453146206b4ed04a3a5f173d

For some reason, when I copy from browser and paste in "add card", the result is
`A function    such that   .` while the source is `A function \star:C\times C\to C such that a\star b=b\star a.`

Note however it works when I copy from the html source

Reproduce the problem by copying the MathJax content from a browser into Anki's "add card" or "add note" editor, and compare it with copying from the HTML source. Trace how the pasted HTML containing is transformed; done means browser copy-paste preserves the MathJax expressions instead of producing empty MathJax images.

Written by the indexing model from the issue text.