Remove coerce zindex from scattergl

Author: Farkites

src/traces/scattergl/defaults.js

@@ -67,6 +67,5 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
     errorBarsSupplyDefaults(traceIn, traceOut, lineColor || markerColor || defaultColor, {axis: 'y'});
     errorBarsSupplyDefaults(traceIn, traceOut, lineColor || markerColor || defaultColor, {axis: 'x', inherit: 'y'});
 
-    coerce('zindex');
     Lib.coerceSelectionMarkerOpacity(traceOut, coerce);
 };