A number of animation tests assume that pausing happens instantaneously. This
patch adjust many of those tests so that they will continue to work when
pausing happens asynchronously. In many cases this is possible because we
know the ready promise on AnimationPlayer (soon to be Animation) objects will
be resolved so we can wait on it and it will resolve immediately now, but when
asynchronous pausing is introduced the test the promise won't resolve until
after the pause operation is complete.
There are some tests that can't be so easily adjusted and we will have to fix
these at the same time as we turn on async pausing. However, taking care of
this set of tests now should reduce the size of subsequent patches in this
series.
AnimationPlayer.ready will currently always be resolved but by updating these
tests to wait on it anyway they should continue to work once we introduce the
delayed animation start behavior.
Since bug 1104433, step_func now passes on the return value of its callback.
That means we can use it directly as a Promise callback function in Promise
chains where the return value of the function is another Promise.
This patch updates existing tests to eliminate the awkward handling we had
around wrapping some parts of Promise callbacks in step() but leaving the return
statement outside it.
This patch moves commonly used addDiv and waitForFrame test methods to
a separate testcommon.js support file.
It also takes advantage of the updates to testharness.js from bug 1104433 to
rework addDiv such that it automatically removes the created div at the end of
the test.
