Patch update to 2.2

2.2.1 - April 28 2016

• Deprecated invalid timing inputs as they will soon throw TypeErrors in native browsers.

  For example, this is deprecated and will eventually throw a TypeError:

  element.animate([], {
      duration: -1,
      iterationStart: -1,
      iterations: -1,
      easing: 'garbage string',
  });
  

• Fixed polyfill crash in browsers based on Chromium 36 to 46.

• Increased cubic-bezier accuracy.

• Added support for grad and turn units for angles.