init violin box and meanline containers to {visible:false}

... instead of clearing them entirely, this is more
    consistent with what the react-chart-editor expects

Author: etpinard

src/traces/box/plot.js

@@ -102,7 +102,7 @@ function plotBoxAndWhiskers(sel, axes, trace, t) {
 
     var paths = sel.selectAll('path.box').data((
         trace.type !== 'violin' ||
-        trace.box
+        (trace.box || {}).visible
     ) ? Lib.identity : []);
 
     paths.enter().append('path')
@@ -304,7 +304,7 @@ function plotBoxMean(sel, axes, trace, t) {
 
     var paths = sel.selectAll('path.mean').data((
         (trace.type === 'box' && trace.boxmean) ||
-        (trace.type === 'violin' && trace.box && trace.meanline)
+        (trace.type === 'violin' && (trace.box || {}).visible && (trace.meanline || {}).visible)
     ) ? Lib.identity : []);
 
     paths.enter().append('path')

src/traces/violin/defaults.js

@@ -46,10 +46,10 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
     var boxLineColor = coerce2('box.line.color', lineColor);
     var boxLineWidth = coerce2('box.line.width', lineWidth);
     var boxVisible = coerce('box.visible', Boolean(boxWidth || boxFillColor || boxLineColor || boxLineWidth));
-    if(!boxVisible) delete traceOut.box;
+    if(!boxVisible) traceOut.box = {visible: false};
 
     var meanLineColor = coerce2('meanline.color', lineColor);
     var meanLineWidth = coerce2('meanline.width', lineWidth);
     var meanLineVisible = coerce('meanline.visible', Boolean(meanLineColor || meanLineWidth));
-    if(!meanLineVisible) delete traceOut.meanline;
+    if(!meanLineVisible) traceOut.meanline = {visible: false};
 };

test/jasmine/tests/violin_test.js

@@ -124,8 +124,8 @@ describe('Test violin defaults', function() {
                 color: 'red'
             }
         });
-        expect(traceOut.box).toBeUndefined();
-        expect(traceOut.meanline).toBeUndefined();
+        expect(traceOut.box).toEqual({visible: false});
+        expect(traceOut.meanline).toEqual({visible: false});
     });
 
     it('should use violin style settings to default inner style attribute', function() {