Only print stdout/stderr if we've got an unexpected output

tools/testing/dart/test_runner.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.
 
 /**
  * Classes and methods for executing tests.
  *
  * This module includes:
  * - Managing parallel execution of tests, including timeout checks.
  * - Evaluating the output of each test as pass/fail/crash/timeout.
@@ skipping 1674 matching lines @@
     var lastCommandCompleted = (numberOfCommandOutputs == numberOfCommands);
     var lastCommandOutput = testCase.lastCommandOutput;
     var lastCommand = lastCommandOutput.command;
     var timedOut = lastCommandOutput.hasTimedOut;
     var nonZeroExitCode = lastCommandOutput.exitCode != 0;
     // NOTE: If this was the last command or there was unexpected output
     // we're done with the test.
     // Otherwise we need to enqueue it again into the test queue.
     if (lastCommandCompleted || timedOut || nonZeroExitCode) {
       var verbose = testCase.configuration['verbose'];
-      if (nonZeroExitCode && verbose != null && verbose) {
+      if (lastCommandOutput.unexpectedOutput && verbose != null && verbose) {
         print(testCase.displayName);
         print("stderr:");
         print(decodeUtf8(lastCommandOutput.stderr));
         if (!lastCommand.isPixelTest) {
           print("stdout:");
           print(decodeUtf8(lastCommandOutput.stdout));
         } else {
           print("");
           print("DRT pixel test failed! stdout is not printed because it "
                 "contains binary data!");
@@ skipping 36 matching lines @@
           completer.complete(testCase);
         }
       });
     }
     runCommand();
 
     return completer.future;
   }
 }