code: function addPropToValue( prop, value ) {
      if ( value === undefined || value === null ) return;
      if ( value.isContentChangeAware !== true ) return;
      var properties = value[ PROPERTY_SYMBOL ];
      if ( !Array.isArray( properties ) ) {
          properties = [ prop ];
      } else if ( properties.indexOf( prop ) === -1 ) {
          properties.push( prop );
      }
      value[ PROPERTY_SYMBOL ] = properties;
  }
docs: Add an `info` attribute to the  property's value. This is useful to
  find the container and the property name from the value.