add 3️⃣ densitymapbox mocks

Author: etpinard

test/image/baselines/mapbox_density-mulitple.png

@@ -0,0 +1,39 @@
+{
+  "data": [{
+    "type": "densitymapbox",
+    "name": "w/ reversescale:true",
+    "lon": [10, 20, 30],
+    "lat": [15, 25, 35],
+    "z": [1, 3, 2],
+    "zmid": 0,
+    "reversescale": true,
+    "radius": 50,
+    "below": "",
+    "colorbar": {
+      "y": 1,
+      "yanchor": "top",
+      "len": 0.45
+    }
+  }, {
+    "type": "densitymapbox",
+    "name": "w/0 z data",
+    "lon": [-10, -20, -30],
+    "lat": [15, 25, 35],
+    "zmin": 0,
+    "zauto": false,
+    "radius": [50, 100, 10],
+    "colorbar": {
+      "y": 0,
+      "yanchor": "bottom",
+      "len": 0.45
+    }
+  }],
+  "layout": {
+    "mapbox": {
+      "style": "light",
+      "center": {"lat": 20}
+    },
+    "width": 600,
+    "height": 400
+  }
+}

test/image/baselines/mapbox_density0.png

@@ -0,0 +1,12 @@
+{
+  "data": [{
+    "type": "densitymapbox",
+    "lon": [10, 20, 30],
+    "lat": [15, 25, 35],
+    "z": [1, 3, 2]
+  }],
+  "layout": {
+    "width": 600,
+    "height": 400
+  }
+}