Remove the wait message when generating an assertion that caused IE8/9 ugliness.

We originally put the wait message in because the keys used to generate the assertion were very long. We have since shortened the key length to a point where assertion generation is fast on even mobile devices.

Removing the screen.

fixes #2618
Merge pull request #3181 from mozilla/issue_2618_ie9_flash

Remove the wait message when generating an assertion that caused IE8/9 ugliness.