test.dart progress bar: a small tweak when --report is not used.

tools/testing/dart/test_progress.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_progress");
 
 #import("dart:io");
 #import("test_runner.dart");
 #import("test_suite.dart");
 
@@ skipping 197 matching lines @@
     if (_failedTests > 0) {
       // We may have printed many failure logs, so reprint the summary data.
       _printProgress();
       print('');
     }
     stdout.close();
     exit(_failedTests > 0 ? 1 : 0);
   }
 
   void allTestsKnown() {
-    if (!_allTestsKnown) {
+    if (!_allTestsKnown && SummaryReport.total > 0) {
       // Clear progress indicator before printing summary report.
       stdout.write(
           '\r                                               \r'.charCodes());
       SummaryReport.printReport();
     }
     _allTestsKnown = true;
   }
 
   void _printStartProgress(TestCase test) => _printProgress();
   void _printDoneProgress(TestCase test) => _printProgress();
@@ skipping 112 matching lines @@
     var status = 'pass';
     if (test.output.unexpectedOutput) {
       status = 'fail';
     }
     var percent = ((_completedTests() / _foundTests) * 100).toInt().toString();
     print('Done ${test.configurationString} ${test.displayName}: $status');
     print('@@@STEP_CLEAR@@@');
     print('@@@STEP_TEXT@ $percent% +$_passedTests -$_failedTests @@@');
   }
 }