Changes to run Swarm from the Editor and to suppress warnings.

samples/swarm/App.dart

Index: samples/swarm/App.dart
diff --git a/samples/swarm/App.dart b/samples/swarm/App.dart
index 95eadb8629a6da333d54426478e5d615aa464944..11e4a429816fbc00e01d8645948fdfa32a3bb2f5 100644
--- a/samples/swarm/App.dart
+++ b/samples/swarm/App.dart
@@ -101,7 +101,7 @@ class App {
       //   * How do we authenticate against the server?
       //   * How do we talk to a server other than thump?
       assert(url.startsWith('/'));
-      return 'http://thump.googleplex.com' + url;
+      return 'http://thump.googleplex.com$url';
     } else {
       return url;
     }