Revert "inline d3.round in drawing/symbol_defs.js"

This reverts commit e10ab24.

Author: archmoj

src/components/drawing/symbol_defs.js

@@ -1,10 +1,7 @@
 'use strict';
 
 var parseSvgPath = require('parse-svg-path');
-var round = // require('@plotly/d3').round;
-    function(x, n) {
-        return n ? Math.round(x * (n = Math.pow(10, n))) / n : Math.round(x);
-    };
+var round = require('@plotly/d3').round;
 
 /** Marker symbol definitions
  * users can specify markers either by number or name