fix emoji in safari
1. emoji sometimes vanished from the autocompleter due to a rounding error
combined with maxWidth: 1em on the emoji span kicking in at arbitrary
font sizes/zooms
2. apparently safari needs explicit VS-16 ligatures, as per
https://github.com/matrix-org/twemoji-colr/commit/ff7dec427fca756929d16bbcadff125a2cd0eab7
