Fix #1603 Remove entity-decode Dependency.

src/mermaid.js

@@ -2,8 +2,6 @@
  * Web page integration module for the mermaid framework. It uses the mermaidAPI for mermaid functionality and to render
  * the diagrams to svg code.
  */
-// import { decode } from 'he';
-import decode from 'entity-decode/browser';
 import { log } from './logger';
 import mermaidAPI from './mermaidAPI';
 import utils from './utils';
@@ -98,7 +96,8 @@ const init = function() {
     txt = element.innerHTML;
 
     // transforms the html to pure text
-    txt = decode(txt)
+    txt = utils
+      .entityDecode(txt)
       .trim()
       .replace(/<br\s*\/?>/gi, '<br/>');