code: function setMetaViewportZoom ( zoomLevel, _window ) {
      var el = ensureMetaViewport( _window );
  
      _window || ( _window = window );
  
      if ( _originalMetaViewport[_window] === undefined ) _originalMetaViewport[_window] = el.content || "";
      el.content = "width=device-width, initial-scale=" + zoomLevel + ", shrink-to-fit=no";
      return el;
  }
docs: Sets the zoom level (pinch zooming on mobile). Modifies the meta viewport tag for that. Makes sure the original value
  is kept around, for use by restoreMetaViewport().
  
  Always use it in conjunction with restoreMetaViewport().
  
  @param   {number|string} zoomLevel
  @param   {Window}        [_window=window]
  @returns {HTMLElement}