function getAbsoluteUri(relative, base) {
  let documentObject;
  if (typeof document !== "undefined") {
    documentObject = document;
  }

  return getAbsoluteUri._implementation(relative, base, documentObject);
}
Given a relative Uri and a base Uri, returns the absolute Uri of the relative Uri.
@function

@param {string} relative The relative Uri.
@param {string} [base] The base Uri.
@returns {string} The absolute Uri of the given relative Uri.

@example
//absolute Uri will be "https://test.com/awesome.png";
const absoluteUri = Cesium.getAbsoluteUri('awesome.png', 'https://test.com');