refactor(snack-bar): switch to fakeAsync tests (#8459)
refactor(snack-bar): switch to fakeAsync tests (#8459)

Switches all of the snack bar tests that were running in `async` to `fakeAsync` in order to make them run faster, avoid some unnecessary nesting and help with browsers timing out.
mmalerba/material2,amcdnl/material2,ppham27/material2,willshowell/material2,jelbourn/material2,Jefiozie/material2,tinayuangao/material2,crisbeto/material2,Jefiozie/material2,josephperrott/material2,amcdnl/material2,andrewseguin/material2,fairfaxmedia/material2,DevVersion/material2,josephperrott/material2,willshowell/material2,andrewseguin/material2,ppham27/material2,ppham27/material2,josephperrott/material2,jelbourn/material2,crisbeto/material2,mmalerba/material2,angular/components,amcdnl/material2,tinayuangao/material2,ppham27/material2,crisbeto/material2,Eddman/material2,Jefiozie/material2,fairfaxmedia/material2,mmalerba/material2,fairfaxmedia/material2,jelbourn/material2,tinayuangao/material2,jelbourn/material2,DevVersion/material2,emoralesb05/material2,Eddman/material2,emoralesb05/material2,willshowell/material2,andrewseguin/material2,mmalerba/material2,Eddman/material2,angular/components,ppham27/material2,willshowell/material2,mmalerba/material2,emoralesb05/material2,DevVersion/material2,tinayuangao/material2,Eddman/material2,andrewseguin/material2,fairfaxmedia/material2,Jefiozie/material2,Jefiozie/material2,tinayuangao/material2,DevVersion/material2,fairfaxmedia/material2,angular/components,emoralesb05/material2,amcdnl/material2,josephperrott/material2,jelbourn/material2,DevVersion/material2,willshowell/material2,josephperrott/material2,amcdnl/material2,angular/components,Eddman/material2,crisbeto/material2,andrewseguin/material2,emoralesb05/material2