Restyle should reflect animations and transitions
When doing a restyle, we should apply animations and transitions to the
new style so that it is reflected in `getComputedStyle()` and the new
style information properly cascades. This is the first part of properly
ticking animations and transitions.
This causes a couple new animations tests failures (along with many new
passes), but we currently don't have support for properly handling
animations after they have completed, so this isn't totally unexpected.
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