Revert "Remove superfluous setTimeout() from test-seq-speed.html"

This setTimeout() is used to test re-running the animation with a playbackRate
of 2.

This reverts commit b3908add33583c9dbf94d6d0f041621d8c329eba.
Modify test-seq-speed to use a playbackRate of 2 for the first iteration

This avoids the need to wait for the setTimeout() to fire.
Merge pull request #93 from steveblock/testSeqSpeed

Update test-seq-speed.html