Move test.dart's check for missing test directories from co19 to general framework.

tools/testing/dart/test_suite.dart

 // Copyright (c) 2012, 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.
 
 #library("test_suite");
 
 #import("dart:io");
 #import("status_file_parser.dart");
 #import("test_runner.dart");
 #import("multitest.dart");
@@ skipping 206 matching lines @@
       ReadTestExpectationsInto(testExpectations,
                                '$dartDir/$statusFilePath',
                                configuration,
                                statusFileRead);
     }
   }
 
   void processDirectory() {
     directoryPath = '$dartDir/$directoryPath';
     Directory dir = new Directory(directoryPath);
+    if (!dir.existsSync()) {

[Mads Ager (google), 2012/02/02 14:33:05]

Since you really want this to be async why not use the async api?

+      print('Directory containing tests not found: $directoryPath');
+      // All paths through test enumeration must be asynchronous.
+      new Timer((ignored){ directoryListingDone(false); }, 0);
+      return;
+    }
+      
     dir.errorHandler = (s) {
       throw s;
     };
     dir.fileHandler = processFile;
     dir.doneHandler = directoryListingDone;
     dir.list(recursive: listRecursively());
   }
 
   void enqueueTestCaseFromTestInformation(TestInformation info) {
     var filename = info.filename;
@@ skipping 829 matching lines @@
  * $noCrash tests are expected to be flaky but not crash
  * $pass tests are expected to pass
  * $failOk tests are expected to fail that we won't fix
  * $fail tests are expected to fail that we should fix
  * $crash tests are expected to crash that we should fix
  * $timeout tests are allowed to timeout
 """;
     print(report);
    }
 }