message_view_header: Color web public stream globe icon.
message_view_header: Color web public stream globe icon.

We forgot to change the selector here when we switched from a fa globe
icon to a .zulip-icon, which resulted in the new globe icon only having
the default color.
This commit makes the appropriate change.

zulip/zulip,andersk/zulip,andersk/zulip,zulip/zulip,andersk/zulip,zulip/zulip,andersk/zulip,zulip/zulip,zulip/zulip,rht/zulip,andersk/zulip,rht/zulip,rht/zulip,rht/zulip,zulip/zulip,rht/zulip,rht/zulip,zulip/zulip,andersk/zulip,rht/zulip,andersk/zulip