[Refactor] Don't use isDimension in axis as it's confusing
[Refactor] Don't use isDimension in axis as it's confusing

vega/vega-lite,uwdata/vega-lite,uwdata/vega-lite,vega/vega-lite,uwdata/vega-lite,uwdata/vega-lite,vega/vega-lite,vega/vega-lite,vega/vega-lite,uwdata/vega-lite