Emoji completions problem is back

[MarcMush]

the tab-completions for emojis don't behave like other competions, a second bugged completion prevents the correct one of being applied. This seems to be the same problem as #297, that was marked as solved 7 years ago

Originally posted by @MarcMush in #297 (comment)

[JamesWrigley]

I don't think #306 was ever upstreamed so this probably broke when IJulia stopped overriding the highlighter JS file. Now it looks like we'd have to fix it in https://github.com/JuliaPluto/lang-julia.