QA: workaround for ChromeDriver bug with confirm dialog

I couldn't figure out any other way to work around this except by adding a sleep.

I added this comment to the steps file:

this gets around a race condition bug in ChromeDriver where both the confirm
and the toast are in the page at once, and Chrome reports either
"stale element reference: element is not attached to the page document"
or "Element does not exist in cache"

Change-Id: I64ddaec2f783cb884ce6cfc59c71a7e01673c41f