Bug #68669 DateTime::createFromFormat() does not allow NULL $timezone

[Neeke]

DateTime::createFromFormat($format, $time, DateTimeZone $timezone = null) has a default value for its third parameter $timezone, but it doesn't accept null as a value.

Running the following script will raise a warning:

DateTime::createFromFormat('Y/m/d', '2015/1/1', null);

// Warning: DateTime::createFromFormat() expects parameter 3 to be DateTimeZone, null given

While the documentation states that the default timezone is going to be used when no parameter is given, also the case where a null $timezone is given should be handled correctly.

This would align the API to the language semantics about default values.

[Rican7]

Makes sense to me.

[laruence]

when I was trying to merge this patch, I found this is already be fixed in master by Sara in 365f428

[krakjoe]

Since this targets an unsupported branch of PHP, and since the issue is already fixed in a supported branch anyway, I'm closing this PR.