Hi there,
Thanks and sorry for the huge delay. What is this PR about? There seems to be very little explanation and a very large diff.

Line 58, Line 63

Checking (prefixed in proto) is not correct because proto is not a list of CSS properties.

The prototype of style "proto"
in Chrome/Edge: document.documentElement.style.constructor = CSSStyleDeclaration(){}
in FF: CSS2Properties(){}
in IE: MSStyleCSSProperties(){}

List of CSS properties: Object.getOwnPropertyNames of
in FF: proto.prototype
in Chrome/IE: document.documentElement.style

Setting of unprefixed properties to proto:

Prefix in FF is e.g. MozAnimation
in Chrome : webkitAnimation
in Edge: webkitAnimation and msAnimation???
in IE: msAnimation

Need further review for Edge.

The getter and setter functions could be placed outside the for loop for better performance.