update airfoil mock to show contourcarpet colored legend styling

Author: alexcjohnson

test/image/baselines/airfoil.png

@@ -31,7 +31,8 @@
       "l":40,
       "t":80
     },
-    "width":900
+    "width":900,
+    "paper_bgcolor": "#ccc"
   },
   "data":[
     {
@@ -221,12 +222,14 @@
       "contours":{
         "start":-1,
         "size":0.025,
-        "end":1.000,
-        "showlines":false
+        "end":1.000
       },
       "line":{
-        "smoothing":0
+        "width": 1,
+        "dash": "dot",
+        "color": "rgba(0,0,0,0.2)"
       },
+      "showlegend": true,
       "z":[
         [ 0.361, 0.300, 0.246, 0.209, 0.182, 0.162, 0.145, 0.132, 0.121, 0.111, 0.103, 0.096, 0.090, 0.085, 0.080, 0.075, 0.072, 0.068, 0.065, 0.062, 0.059, 0.057, 0.055, 0.053, 0.051, 0.049, 0.047, 0.046, 0.044, 0.043, 0.042 ],
         [ 0.261, 0.234, 0.199, 0.170, 0.147, 0.129, 0.115, 0.103, 0.093, 0.085, 0.078, 0.072, 0.066, 0.062, 0.058, 0.054, 0.051, 0.048, 0.045, 0.043, 0.041, 0.039, 0.037, 0.036, 0.034, 0.033, 0.031, 0.030, 0.029, 0.028, 0.027 ],
@@ -472,7 +475,8 @@
       "type":"contourcarpet",
       "line":{
         "color":"rgba(0, 0, 0, 0.5)",
-        "smoothing":1
+        "smoothing":1,
+        "width": 1
       },
       "contours":{
         "size":0.250,