Fix infinite loop when postinstall has <br/> in it

src/js/index.js

@@ -394,8 +394,13 @@ app.filter('markdown2html', function () {
         tables: true
     });
 
+    // without this cache, the code runs into some infinite loop (https://github.com/angular/angular.js/issues/3980)
+    var cache = {};
+
     return function (text) {
-        return converter.makeHtml(text);
+        if (cache[text]) return cache[text];
+        cache[text] = converter.makeHtml(text);
+        return cache[text];
     };
 });