Definition
Web Animations Level 2 defines GroupEffect
[Exposed=Window]
interface GroupEffect {
constructor(sequence<AnimationEffect>? children,
optional (unrestricted double or EffectTiming) timing = {});
readonly attribute AnimationNodeList children;
readonly attribute AnimationEffect? firstChild;
readonly attribute AnimationEffect? lastChild;
GroupEffect clone ();
undefined prepend (AnimationEffect... effects);
undefined append (AnimationEffect... effects);
};