CSSKeyframeRule
An object representing a set of style for a given keyframe. It corresponds to the contains of a single keyframe of a @keyframes at-rule. It implements the CSSRule interface with a type value of 8 (CSSRule.KEYFRAME_RULE).
var CSSKeyframeRule: {
prototype: CSSKeyframeRule;
new (): CSSKeyframeRule;
};