date filter backdates dates if time is not specified

[mhevery]

{{ '2012-04-01' | date:'d MMM yyyy' }} renders as 31 Mar 2012

http://plnkr.co/edit/pdoczJeLZoCo6CRuwUWi?p=preview

this issue only occurs for clients in timezones before GMT (like PT for example)

[IgorMinar]

the question is how this should actually behave so that we don't introduce new timezone bugs...

• {{ '2012-04-01' | date:'d MMM yyyy' }} should always render as 1 Apr 2012 regardless of the timezone
• {{ '2012-04-01 0:0:0' | date:'d MMM yyyy' }} should assume that the time is in GMT so the output is timezone-dependent
• {{ '2012-04-01 0:0:0 +0200' | date:'d MMM yyyy' }} should assume that the time is in GMT+2 so the output is timezone-dependent.

I think that this is a reasonable behavior

[IgorMinar]

actually it turns out that ISO8601 states that if a timezone is not specified the time/date is in the local time, so {{ '2012-04-01 0:0:0' | date:'d MMM yyyy' }} should always render as 1 Apr 2012.

The odd thing is the javascript's Date constructor is quite screwed up (at least in V8):

> new Date('2012-04-01')
Sat Mar 31 2012 17:00:00 GMT-0700 (PDT)
> new Date('2012-04-01T00:00:00')
Sat Mar 31 2012 17:00:00 GMT-0700 (PDT)

> new Date('2012-04-01 0:0:0')
Sun Apr 01 2012 00:00:00 GMT-0700 (PDT)
> new Date('2012-04-01 00:00:00')
Sun Apr 01 2012 00:00:00 GMT-0700 (PDT)

> new Date('2012-04-01T00:00:00Z')
Sat Mar 31 2012 17:00:00 GMT-0700 (PDT)
> new Date('2012-04-01 00:00:00Z')
Sat Mar 31 2012 17:00:00 GMT-0700 (PDT)

notice that in some cases when the timezone is not specified the date/time is parsed as local, other times its parsed as UTC.