I am not going to make this bug block bug 1535532 since this issue is a pre-existing issue (bug 1039799).

Presumably what we need to fix this is;

1. in nsDisplayBackgroundColor tell whether the background color is inherited from an animating background color, and identify the element (nsIFrame I suppose) inheriting the color
2. Copy the Layer::animation object of the ancestor's
3. Create a new AnimationInfo having a different animation id with the copied object
4. Send the AnimationInfo to the compositor

This should work for the test case I am attaching. But if inherit is used in keyframes, things are more complicated.

(In reply to Hiroyuki Ikezoe (:hiro) from comment #0)

2. Copy the Layer::animation object of the ancestor's
3. Create a new AnimationInfo having a different animation id with the copied object

For WebRender, we don't need to copy the animation object at all, we don't need to generate the different animation id either. We can re-use the same animation id for different display items.