Add date/timestamp field

[annevk]

See http://lists.w3.org/Archives/Public/public-whatwg-archive/2014Aug/0017.html

@sicking, I guess this should just mimic the timestamp used for Date objects? Do we expect applications to worry about timezones?

[sicking]

I don't think we need to worry about timestamps. The main usecase here
it to make sure that text like "5 minutes ago" or "in 10 minutes" that
the platform would show next to the notification reflects when the
relevant event happened, rather than when the notification was
created.

If the user crosses a timezone line that doesn't affect how long ago
that the event happened.

/ Jonas

[annevk]

So you think it should be an offset? In milliseconds per what we decided for web animations? Paging @domenic for verification.

[domenic]

I read @sicking as wanting an absolute point in time. (Timezone-independent.) In that case we would use a timestamp, like that returned by Date.now().

I guess I am assuming "I don't think we need to worry about timestamps" was supposed to be "I don't think we need to worry about timezones."

Anyway, yes, we did indeed fix web animations to use milliseconds for offsets, in the event that I am wrong and @sicking wanted offsets.

[sicking]

What @domenic said. I ment to say to not worry about timezones. And that we
should use timezone independent points in time. I.e. what's returned from
Date.now().

So if you want to notify about a meeting happening in 10 minutes, you'd
use: Date.now() + 1000_60_10.

[sicking]

Ping? Any reason not to do this? This seems like a simple feature to add, and notifications look really ugly when you get a notification which says "Meeting starting in 10 minutes [8 minutes ago]" where the part inside the [] is rendered by the platform in a different color.

[annevk]

I guess we should do this, yes. Perhaps @beverloo or @johnmellor wants to create another PR?

[beverloo]

I'm in favor of doing this too, and will prepare a PR tomorrow. Thanks for kicking this up, @sicking! :)