Follow-up to 6048e12669: Fix reaction color for non-emojis on dark theme
Hardcoding it to black is bad for dark themes. It was probably done
because the default color would make emojis look pale due to
transparency. If we use a primary text color which hopefully does not
feature transparency (it does not for SC themes, at least), everything
looks fine.
Change-Id: Icbc3b37f5535b98684c2225c0973a152e88d6b31
004a51646b