Fix continuous colour chart

tests/expected_meta_hist_choropleth.json

@@ -363744,10 +363744,9 @@
           },
           "field": "pct_estimate",
           "scale": {
-            "nice": true,
-            "zero": false
+            "nice": true
           },
-          "title": "",
+          "title": "pct_estimate",
           "type": "quantitative"
         }
       },
@@ -363756,6 +363755,7 @@
         "color": "gray",
         "type": "bar"
       },
+      "title": "Colours used",
       "transform": [
         {
           "joinaggregate": [
@@ -363795,7 +363795,7 @@
           },
           "field": "x",
           "sort": "descending",
-          "title": "colours used",
+          "title": "",
           "type": "quantitative"
         },
         "y": {
@@ -363805,8 +363805,7 @@
           },
           "field": "y",
           "scale": {
-            "nice": true,
-            "zero": false
+            "nice": true
           },
           "title": "",
           "type": "quantitative"

tests/expected_meta_hist_choropleth_extent.json

@@ -363754,7 +363754,7 @@
             ],
             "nice": true
           },
-          "title": "",
+          "title": "pct_estimate",
           "type": "quantitative"
         }
       },
@@ -363763,6 +363763,7 @@
         "color": "gray",
         "type": "bar"
       },
+      "title": "Colours used",
       "transform": [
         {
           "joinaggregate": [
@@ -363806,7 +363807,7 @@
           },
           "field": "x",
           "sort": "descending",
-          "title": "colours used",
+          "title": "",
           "type": "quantitative"
         },
         "y": {

tests/expected_meta_hist_scatterplot.json

@@ -57663,7 +57663,11 @@
             "maxbins": 100
           },
           "field": "Production_Budget",
-          "title": "",
+          "scale": {
+            "nice": true,
+            "zero": false
+          },
+          "title": "Production_Budget",
           "type": "quantitative"
         }
       },
@@ -57672,6 +57676,7 @@
         "color": "gray",
         "type": "bar"
       },
+      "title": "Colours used",
       "transform": [
         {
           "joinaggregate": [
@@ -57711,7 +57716,7 @@
           },
           "field": "x",
           "sort": "descending",
-          "title": "colours used",
+          "title": "",
           "type": "quantitative"
         },
         "y": {