fix(index): refactor ES module from ES6 to ES5 syntax

Fixes #222

Do not use object destructuring assignment in `index.mjs` since
it's not supported by older browsers like Internet Explorer 11.

Author: remarkablemark

index.mjs

@@ -1,4 +1,7 @@
 import HTMLReactParser from './index.js';
 
+export var domToReact = HTMLReactParser.domToReact;
+export var htmlToDOM = HTMLReactParser.htmlToDOM;
+export var attributesToProps = HTMLReactParser.attributesToProps;
+
 export default HTMLReactParser;
-export var { domToReact, htmlToDOM, attributesToProps } = HTMLReactParser;