emit 'plotly_doubleclick' events,

  on dragbox double clicks and select/lasso double clicks

Author: etpinard

src/plots/cartesian/graph_interact.js

@@ -1821,7 +1821,7 @@ function dragBox(gd, plotinfo, x, y, w, h, ns, ew) {
             }
         }
 
-        gd.emit('plotly_doubleclick', {});
+        gd.emit('plotly_doubleclick', null);
         Plotly.relayout(gd, attrs);
     }
 

src/plots/cartesian/select.js

@@ -172,7 +172,7 @@ module.exports = function prepSelect(e, startX, startY, dragOptions, mode) {
                 searchInfo.selectPoints(searchInfo, false);
             }
 
-            gd.emit('plotly_doubleclick', {});
+            gd.emit('plotly_doubleclick', null);
         }
         else {
             dragOptions.gd.emit('plotly_selected', eventData);