Leap year validation

[chr1soscl]

IMPORTANT:
Please be specific with an example. An issue with

Steps to reproduce and a minimal demo

Inject a date validator to a date formcontrol and manually enter leap dates, like:
02/29/2018 Invalid date
02/29/2019 Invalid date
02/29/2020 valid date
02/31/2096 invalid date

Current behavior

there is no leap year validation for date.

Expected/desired behavior

• error should trigger for invalid leap years, testing examples above.

Environment information

• OS: Windows 10
• Angular Version: 8
• Browser: Chrome, IE11