R1:9f8e0ad473a6

Remove unusual unicode marks in Differential action dropdown

Summary:
See <https://twitter.com/HayleyCAnderson/status/988873585363009536>.

Currently, the action dropdown in Differential shows a heavy "X" after "Request Changes" and a heavy checkmark after "Accept Revision".

Although I'm not convinced that the messaging around "Request Changes" is too strong, I do think these marks are out of place in modern Differential. They came from a simpler time when this dropdown had fewer actions, but feel a…