Fix handleGroupingDefaults calls outside of bar/defaults.js

Author: my-tien

src/traces/bar/defaults.js

@@ -80,7 +80,7 @@ function crossTraceDefaults(fullData, fullLayout) {
                 traceOut.marker.cornerradius = validateCornerradius(r);
             }
 
-            handleGroupingDefaults(fullLayout.barmode, traceIn, traceOut, fullLayout, coerce);
+            handleGroupingDefaults(traceIn, traceOut, fullLayout, coerce, fullLayout.barmode);
         }
     }
 }

src/traces/scatter/grouping_defaults.js

@@ -2,7 +2,7 @@
 
 var getAxisGroup = require('../../plots/cartesian/constraints').getAxisGroup;
 
-module.exports = function handleGroupingDefaults(barmode, traceIn, traceOut, fullLayout, coerce) {
+module.exports = function handleGroupingDefaults(traceIn, traceOut, fullLayout, coerce, barmode) {
     var orientation = traceOut.orientation;
     // N.B. grouping is done across all trace types that support it
     var posAxId = traceOut[{v: 'x', h: 'y'}[orientation] + 'axis'];
@@ -31,7 +31,8 @@ module.exports = function handleGroupingDefaults(barmode, traceIn, traceOut, ful
     var offsetGroupOpts = offsetGroups[offsetgroup];
     // in barmode 'group', traces without offsetgroup receive their own offsetgroup
     // in other barmodes, traces without offsetgroup are assigned to the same offset group
-    if(barmode !== 'group' || offsetgroup) {
+    var isBarTrace = traceOut.type === 'bar' || traceOut.type === 'waterfall';
+    if((isBarTrace && barmode !== 'group') || offsetgroup) {
         if(!offsetGroupOpts) {
             offsetGroupOpts = offsetGroups[offsetgroup] = {
                 offsetIndex: Object.keys(offsetGroups).length