use r2c in shapes calc autorange

Author: etpinard

src/components/shapes/calc_autorange.js

@@ -43,7 +43,7 @@ module.exports = function calcAutorange(gd) {
 };
 
 function shapeBounds(ax, v0, v1, path, paramsToUse) {
-    var convertVal = (ax.type === 'category') ? Number : ax.d2c;
+    var convertVal = (ax.type === 'category') ? ax.r2c : ax.d2c;
 
     if(v0 !== undefined) return [convertVal(v0), convertVal(v1)];
     if(!path) return;