code: function replaceYield(templ, html) {
      // do nothing if no yield
      if (!/<yield\b/i.test(templ)) return templ
  
      // be careful with #1343 - string on the source having `$1`
      var n = 0
      templ = templ.replace(/<yield\s+from=['"]([-\w]+)['"]\s*(?:\/>|>\s*<\/yield\s*>)/ig,
        function (str, ref) {
          var m = html.match(RegExp(reToSrc.replace('@', ref), 'i'))
          ++n
          return m && m[2] || ''
        })
  
      // yield without any "from", replace yield in templ with the innerHTML
      return n ? templ : templ.replace(/<yield\s*(?:\/>|>\s*<\/yield\s*>)/gi, html || '')
    }
docs: end ie9elem() 
  Replace the yield tag from any tag template with the innerHTML of the
  original tag in the page
  @param   { String } templ - tag implementation template
  @param   { String } html  - original content of the tag in the DOM
  @returns { String } tag template updated without the yield tag