template: insert content before firstChild; this prevents textNodes from invalidating annotations.

Author: sorvell

components/polymer/src/features/template.html

@@ -19,14 +19,12 @@
     },
 
     _stampTemplate: function(template, target) {
-      // TODO(sorvell): light dom children will invalidate annotations.
-      // TODO(sjmiles): ^ why?
       var instance = this.instanceTemplate(template);
       // identify host
       for (var e = instance.firstElementChild; e; e=e.nextElementSibling) {
         e.host = this;
       }
-      target.insertBefore(instance, target.firstElementChild);
+      target.insertBefore(instance, target.firstChild);
     },
 
     instanceTemplate: function(template) {