clean up escapePercentSign (#1101)

lib/dom-to-image.js

@@ -327,9 +327,8 @@
         node.setAttribute('xmlns', 'http://www.w3.org/1999/xhtml')
         return new XMLSerializer().serializeToString(node)
       })
-      .then(function (str) {
-        return util.escapeXhtml(str, escapePercentSign)
-      })
+      .then(util.escapeXhtml)
+      .then(str => (escapePercentSign ? str.replace(/%/g, '%25') : str))
       .then(function (xhtml) {
         return '<foreignObject x="0" y="0" width="100%" height="100%">' + xhtml + '</foreignObject>'
       })
@@ -552,10 +551,7 @@
       return array
     }
 
-    function escapeXhtml(string, escapePercentSign) {
-      if (escapePercentSign) {
-        string = string.replace(/%/g, '%25')
-      }
+    function escapeXhtml(string) {
       return string.replace(/#/g, '%23').replace(/\n/g, '%0A')
     }