PR into master from dev/olga/9295-Incorrect-rendering-for-textit

[OlgaRedozubova]

branch: dev/olga/9295-Incorrect-rendering-for-textit

Fixed issues:

• [mmd] Incorrect rendering for [\textit{} #9295
• [snip web] Copy dialog won't go away #9300
• [mmd][asciimath] Do not include certain characters in asciimath output #9266