InputNumberUITest Flapper try 2

Still flapping. Try re-searching for the WebElement each cycle of the wait.

@rev mkohanfars@
@bug W-1936580@
Merging origin/tbliss/master-pending-InputNumberUITest-flapper-fix-2 into master
[maven-release-plugin] prepare release aura-framework-0.521
[maven-release-plugin] prepare for next development iteration