fix(codepens): using unicode characters to avoid codepen's unescaping

- Codepen was unescaping &lt; (<) and &gt; (>) which caused, on some demos, an unclosed elements (like `<md-select>`).
Used different unicode lookalike characters so it won't be considered as an element

fixes #8761

Closes #9314

Author: EladBezalel

docs/app/js/codepen.js

@@ -41,7 +41,14 @@
     function escapeJsonQuotes(json) {
       return JSON.stringify(json)
         .replace(/'/g, "'")
-        .replace(/"/g, """);
+        .replace(/"/g, """)
+        /**
+         * Codepen was unescaping &lt; (<) and &gt; (>) which caused, on some demos,
+         * an unclosed elements (like <md-select>). 
+         * Used different unicode lookalike characters so it won't be considered as an element
+         */
+        .replace(/&amp;lt;/g, "&#x02C2;") // http://graphemica.com/%CB%82
+        .replace(/&amp;gt;/g, "&#x02C3;"); // http://graphemica.com/%CB%83
     }
   }