Make 'useXConfiguration' check for an existing configuration. This is so that it

pkg/unittest/lib/compact_vm_config.dart

Index: pkg/unittest/lib/compact_vm_config.dart
diff --git a/pkg/unittest/lib/compact_vm_config.dart b/pkg/unittest/lib/compact_vm_config.dart
index 7e6d7e8362b94e185ddf7623fae99f4a30ff2d54..99658c8fca20e330121405d78eb1e9e1038fc787 100644
--- a/pkg/unittest/lib/compact_vm_config.dart
+++ b/pkg/unittest/lib/compact_vm_config.dart
@@ -165,10 +165,9 @@ class CompactVMConfiguration extends VMConfiguration {
     }
     return '...$res';
   }
-
-  void notifyController(String msg) {}

[gram, 2013/01/11 18:48:49]

I assume this is okay, although it is not related to the rest of the CL.

[Siggi Cherem (dart-lang), 2013/01/11 19:03:13]

yeah - in a previous CL I made this a subclass of vm_config, which already has a
method just like it.

 }
 
 void useCompactVMConfiguration() {
+  if (config != null) return;
   configure(new CompactVMConfiguration());
 }