Don't apply relayout operations to the view that originated the event (GH1086) (#1094)

* Don't apply relayout operations to the view that originated the event

This fixes a zoom stutter that occurred on scroll zoom of 3d plots

* When computing overlapping properties to remove, don't leave empty objects.

Before, while scroll zooming on scatter3d trace with multiple views we'd sometimes end up with a _props state of:

{'up': {'x': -0.4, 'y': -0.4, 'z': 0.8},
 'center': {'x': 0, 'y': 0, 'z': 0},
 'eye': {}}

When this happened, accessing a sub-property of eye would always return none, even though values existed in the _prop_defaults dict.

e.g.  fig.layout.scene.camera.eye.x would return None because the eye dict in _props was empty.

Now we just remove the eye property as well if all of it's own properties have been removed:

{'up': {'x': -0.4, 'y': -0.4, 'z': 0.8},
 'center': {'x': 0, 'y': 0, 'z': 0}}

Author: jonmmease

js/src/Figure.js

@@ -1248,10 +1248,11 @@ var FigureView = widgets.DOMWidgetView.extend({
         /** @type {Py2JsRelayoutMsg} */
         var msgData = this.model.get("_py2js_relayout");
         if (msgData !== null) {
-
-            var relayoutData = msgData.relayout_data;
+            if (msgData.source_view_id !== this.viewID) {
+                var relayoutData = msgData.relayout_data;
                 relayoutData["_doNotReportToPy"] = true;
                 Plotly.relayout(this.el, msgData.relayout_data);
+            }
 
             // ### Send layout delta ###
             var layout_edit_id = msgData.layout_edit_id;

plotly/basewidget.py

@@ -814,6 +814,12 @@ def _remove_overlapping_props(input_data, delta_data, prop_path=()):
                                 input_val, delta_val, recur_prop_path))
                         removed.extend(recur_removed)
 
+                        # Check whether the last property in input_val
+                        # has been removed. If so, remove it entirely
+                        if not input_val:
+                            input_data.pop(p)
+                            removed.append(recur_prop_path)
+
                 elif p in input_data and p != 'uid':
                     # ### Remove property ###
                     input_data.pop(p)