NameA, elementNameB) {
    if (elementNameA === 'html') { return ''; }  // Everything opens body.
    return (
        '<' + elementNameA + '>'
        + '<' + elementNameB + ' id="inner-implied-el">'
        + '</' + elementNameB + '>'
        + '</' + elementNameA + '>');
  }
  // Examines the resulting body to fold a single experiment into the result.
  function computeImpliedElements(elementNameA, elementNameB, body, result) {
    var inner = body.querySelector(elementNameB + "[id='inner-implied-el']");