In bug 1320608, I did fix our mismatch nsIFrame handling for table element. But I suspect there are still mis-usage, we should audit all of them. Now I highly doubt that we do properly handle mMayHaveTransformAnimation and mMayHaveOpacityAnimation flags in nsIFrame.
Depending on bug 1463605, since I am going to fix some of mis-usage in the bug.
|aFrame->RefusedAsyncAnimation()| in FindAnimationsForCompositor()  looks a bit error-prone. I think it's not a problem so far, but for continuation frames, nsDisplayOpacity has the last continuation as |mFrame|, so FindAnimationsForCompositor() is called for the last one, whereas in animation code we consider |nsIFrame*| is the primary frame basically, so it might be a matter that we will mis-use there. We should add a comment there.  https://hg.mozilla.org/mozilla-central/file/da28b92efe6f/dom/animation/EffectCompositor.cpp#l155
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