avoid error in compiled version by specifying directly
avoid error in compiled version by specifying directly

@domoritz, @arvind

uwdata/vega-lite,ellisonbg/vega-lite,uwdata/vega-lite,vega/vega-lite,uwdata/vega-lite,ellisonbg/vega-lite,uwdata/vega-lite,vega/vega-lite,vega/vega-lite,vega/vega-lite,uwdata/vega-lite,ellisonbg/vega-lite,vega/vega-lite