Bug 932793 - Intermittent test "thread_ui.js > scrolling scroll 100px, should be detected as a manual scroll" r=schung a=tests

* Fix intermittent scripts by sending the scroll event in the test
* Fix bad tests that were revealed in the process: `done` callback set on the
  suite function instead of the test function, wrong SMS messages.
* Linearized and de-asynchronized some tests

(cherry picked from commit 942cba7260b3855364ece50bb0f6b9514ed84333)