assertContained = function(a, b, opt_c) {
  'use strict';
  _validateArguments(2, arguments);
  const element = nonCommentArg(1, 2, arguments);
  const otherElement = nonCommentArg(2, 2, arguments);
  const elementRect = goog.style.getBounds(element);
  const otherElementRect = goog.style.getBounds(otherElement);

  _assert(
      commentArg(1, arguments), elementRect.contains(otherElementRect),
      'Element should be contained within the other element.');
}
Asserts that the first element's bounds contain the bounds of the second
element.
@param {Element|string} a The first element or optionally the comment string.
@param {Element} b The second element or the first element if comment string
    is present.
@param {Element=} opt_c The second element if comment string is present.