[sidenav] can't close until opening animation is complete

[willshowell]

Bug, feature request, or proposal:

Regression

Expected

Sidenav can still be closed while animating open

Current

Sidenav must wait until animation is complete to trigger new actions

Reproduction

Working with beta.8: https://plnkr.co/edit/Ucv13OC4Zsl55CXRANK3?p=preview
Failing with latest: https://plnkr.co/edit/pCWLJ2ThQrKgGXI2Q9cn?p=preview

Other

Presumably due to #4959 or #6189

[mmalerba]

@crisbeto seems like this may have been a regression from one of your PRs

[crisbeto]

It was an intentional change (there's an internal _isAnimating flag that is checked). I did it primarily to ensure that you always get back the correct animation promise and to guard against cases like #5743 and #4932.

[willshowell]

@crisbeto are you aware of any open issues in core for #5743 and #4932? If I understand correctly, the current behavior is necessary until those are sorted out?

Further, could you explain this note?
https://github.com/angular/material2/blob/70bd5fc20e7fe6b1749b334d29e842cb3681609d/src/lib/sidenav/drawer.ts#L252-L254

Is that to say that the promise return value will become obsolete, but is there to match the before-animations behavior?

[crisbeto]

Yes, the previous approach was passing promises around to coordinate the animation, but I removed all of them in #4959 since they weren't necessary anymore. The ones for toggle, open and close were left in since they were a part of the public API.

[crisbeto]

Got some time to look into this. It seems like #5743 isn't an issue for the sidenav. I'll remove the _isAnimating guards.