code: function( styleDefinition, variableName )
  				{
  
  					var elementMigrateFilter = this.elementMigrateFilter;
  					return function( value, element )
  					{
  						// Build an stylish element first.
  						var styleElement = new CKEDITOR.htmlParser.element( null ),
  							variables = {};
  
  						variables[ variableName ] = value;
  						elementMigrateFilter( styleDefinition, variables )( styleElement );
  						// Place the new element inside the existing span.
  						styleElement.children = element.children;
  						element.children = [ styleElement ];
  					};
  				}
docs: Migrate styles by creating a new nested stylish element.
  @param styleDefinition