While working on shifting toward native browser time zone APIs
(#16451), it was found that all but very recent Chrome and Node
versions reject certain legacy timezone aliases like US/Pacific
(https://crbug.com/364374).
For now, we only canonicalize the timezone property returned in user
objects and not the timezone setting itself.
Signed-off-by: Anders Kaseorg <anders@zulip.com>
Anders Kaseorg