Fixes to get Swarm demo working again.

frog/value.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Represents a meta-value for code generation.
  */
 class Value {
   /** The [Type] of the [Value]. */
   Type type;
@@ skipping 159 matching lines @@
         } else {
           world.warning(message, node.span);
         }
       }
     }
 
     // Fall back to a dynamic operation for instance members
     if (member == null && !isSuper && !isType) {
       member = context.findMembers(name);
       if (member == null && !isDynamic) {
-        world.warning('$name is not defined anywhere in the world.',
+        var where = 'the world';
+        if (name.startsWith('_')) {
+          where = 'library "${context.library.name}"';
+        }
+        world.warning('$name is not defined anywhere in $where.',
            node.span);
       }
     }
 
     return member;
   }
 
   checkFirstClass(SourceSpan span) {
     if (isType) {
       world.error('Types are not first class', span);
@@ skipping 517 matching lines @@
     // Then look for members in my library.
     member = home.library.lookup(name, span);
     if (member != null) {
       return member;
     }
 
     _ensureCode();
     return null;
   }
 }