Symbol layers are always drawn on top

[pathmapper]

mapbox-gl-js version: v0.45.0

browser: Chrome on Linux

Steps to Trigger Behavior

Add a layer of type fill to the streets-v9 style with map.addLayer without providing a before argument.

Link to Demonstration

http://jsbin.com/seviqomame/edit?html,output
(which is https://www.mapbox.com/mapbox-gl-js/example/geojson-polygon/ with increased fill-opacity)

or

http://jsbin.com/pikisolehu/edit?html,output
(which is https://www.mapbox.com/mapbox-gl-js/example/geojson-layer-in-stack/ without before argument and increased fill-opacity)

Expected Behavior

The polygon is drawn on top of the labels because there is no before argument specified for the additional fill layer thus the layer will be appended to the end of the layers array.

Actual Behavior

The labels are drawn on top.

[jfirebaugh]

Thanks for the report, we're tracking this in #2074. As a workaround, you can set the opacity of the fill layer to 0.99.