[DatePicker] first argument null for datepicker onchange

[roodboi]

is there a reason why the date isnt returned as the first argument? https://github.com/callemall/material-ui/blob/master/src/js/date-picker/date-picker.jsx#L93

[jkruder]

Because onChange is also passed to the TextField https://github.com/callemall/material-ui/blob/master/src/js/date-picker/date-picker.jsx#L64 and it has an event as its first argument. Looks like the intent is to funnel changes made in the textfield or dialog. Wouldn't hurt to be specific, property expansion can be confusing.

I suggest renaming DatePicker.onChange to DatePicker.onDateChange and then wire up onDateChange to TextField.onChange and DatePickerDialog.onAccept.

[hai-cea]

@jkruder Sounds like a reasonable approach.

[oliviertassinari]

@roodboi Yes, there is a good reason. That's for making our onChange event consistent across Material-UI (#2957).