Don't use syntax that doesn't work in Node v4 (yet)

Author: domenic

lib/jsdom/browser/htmltodom.js

@@ -183,7 +183,9 @@ class HtmlToDom {
       const entityMatcher = /<!ENTITY ([^ ]+) "([^"]+)">/g;
       let result;
       while ((result = entityMatcher.exec(dt))) {
-        const [, name, value] = result;
+        // TODO Node v6 const [, name, value] = result;
+        const name = result[1];
+        const value = result[2];
         if (!(name in parser.ENTITIES)) {
           parser.ENTITIES[name] = value;
         }