#631 add dialog polyfill for firefox and safari

demo-shell-ng2/app/app.component.css

@@ -9,4 +9,4 @@
 }
 .user-profile{
     margin-right: 3px;
-}
+}

demo-shell-ng2/app/css/app.css

@@ -35,3 +35,7 @@ body, html {
     text-align: center;
     position: relative;
 }
+
+._dialog_overlay {
+    position: static !important;
+}