simplify box/meanlin visible logic

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 || {}).visible
+        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 || {}).visible && (trace.meanline || {}).visible)
+        (trace.type === 'violin' && trace.box.visible && trace.meanline.visible)
     ) ? Lib.identity : []);
 
     paths.enter().append('path')

src/traces/violin/plot.js

@@ -147,7 +147,7 @@ module.exports = function plot(gd, plotinfo, cd, violinLayer) {
             d.pathLength = d.path.getTotalLength() / (hasBothSides ? 2 : 1);
         });
 
-        var boxAttrs = trace.box || {};
+        var boxAttrs = trace.box;
         var boxWidth = boxAttrs.width;
         var boxLineWidth = (boxAttrs.line || {}).width;
         var bdPosScaled;
@@ -179,7 +179,7 @@ module.exports = function plot(gd, plotinfo, cd, violinLayer) {
         });
 
         var fn;
-        if(!(trace.box || {}).visible && (trace.meanline || {}).visible) {
+        if(!trace.box.visible && trace.meanline.visible) {
             fn = Lib.identity;
         }