platform/video.videojs/dist/video.es.js
function computedStyle(el, prop) {
  if (!el || !prop) {
    return '';
  }

  if (typeof window.getComputedStyle === 'function') {
    var cs = window.getComputedStyle(el);

    return cs ? cs[prop] : '';
  }

  return el.currentStyle[prop] || '';
}
function computedStyle(el, prop) {
  if (!el || !prop) {
    return '';
  }

  if (typeof window.getComputedStyle === 'function') {
    var cs = window.getComputedStyle(el);

    return cs ? cs[prop] : '';
  }

  return el.currentStyle[prop] || '';
}
@file computed-style.js
@module computed-style
 
A safe getComputedStyle with an IE8 fallback.

This is needed because in Firefox, if the player is loaded in an iframe with
`display:none`, then `getComputedStyle` returns `null`, so, we do a null-check to
make sure  that the player doesn't break in these cases.

@param {Element} el
The element you want the computed style of

@param {string} prop
The property name you want

@see https://bugzilla.mozilla.org/show_bug.cgi?id=548397

@static
@const