styles: Add a type annotation required by newer Flow.
styles: Add a type annotation required by newer Flow.

Flow v0.78 actually quite happily infers the correct answer here.
But Flow v0.92 (presumably since v0.85) insists on an explicit
annotation... so fine, sure, it's easy to add.

vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile