Merge pull request #5356 from plotly/followup-5349

requested edits in pull 5349

Author: archmoj

test/image/baselines/mapbox_density-mulitple.png renamed to test/image/baselines/mapbox_density-multiple.png

@@ -265,8 +265,7 @@ describe('Visible rangesliders', function() {
                 ],
                 rangeslider: {visible: true}
             },
-            width: 800,
-            height: 500
+            width: 800
         })
         .then(function() {
             var bb = getRangeSlider().getBoundingClientRect();