make array marker.symbol value propagate to legendonly items

Author: etpinard

src/components/legend/style.js

@@ -115,6 +115,7 @@ module.exports = function style(s, gd) {
 
             if(showMarkers) {
                 dEdit.mc = boundVal('marker.color', pickFirst);
+                dEdit.mx = boundVal('marker.symbol', pickFirst);
                 dEdit.mo = boundVal('marker.opacity', Lib.mean, [0.2, 1]);
                 dEdit.ms = boundVal('marker.size', Lib.mean, [2, 16]);
                 dEdit.mlc = boundVal('marker.line.color', pickFirst);

test/image/baselines/legend_visibility.png

@@ -53,6 +53,17 @@
       "xaxis": "x2",
       "yaxis": "y3",
       "y": [1, 4, 6, 7, 7, 8, 8, 8, 9]
+    },
+    {
+      "name": "marker A",
+      "mode": "markers",
+      "visible": "legendonly",
+      "y": [1, 4, 6, 3, 2, 8, 8, 8, 4],
+      "yaxis": "y2",
+      "marker": {
+        "size": 15,
+        "symbol": ["square", "square", "square", "square", "square", "square", "square", "square", "square"]
+      }
     }
   ],
   "layout": {