Fixed dartc test/build setup, so test can run on Windows. Might be related to dart:2623

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 14 matching lines @@
   /** Path to the executable of this command. */
   String executable;
 
   /** Command line arguments to the executable. */
   List<String> arguments;
 
   /** The actual command line that will be executed. */
   String commandLine;
 
   Command(this.executable, this.arguments) {
+    if (Platform.operatingSystem == 'windows') {
+      // Windows can't handle the first command if it is a .bat file or the like
+      // with the slashes going the other direction.
+      // TODO(efortuna): Remove this when fixed (Issue 1306).
+      executable = executable.replaceAll('/', '\\');
+    }
     commandLine = "$executable ${Strings.join(arguments, ' ')}";
   }
 
   String toString() => commandLine;
 }
 
 /**
  * TestCase contains all the information needed to run a test and evaluate
  * its output.  Running a test involves starting a separate process, with
  * the executable and arguments given by the TestCase, and recording its
@@ skipping 562 matching lines @@
     Expect.isFalse(testCase.expectedOutcomes.contains(SKIP));
     stdout = new List<String>();
     stderr = new List<String>();
     currentStep = 0;
     startTime = new Date.now();
     runCommand(testCase.commands[currentStep++], stepExitHandler);
   }
 
   void runCommand(Command command,
                   void exitHandler(int exitCode)) {
-    if (Platform.operatingSystem == 'windows') {
-      // Windows can't handle the first command if it is a .bat file or the like
-      // with the slashes going the other direction.
-      // TODO(efortuna): Remove this when fixed (Issue 1306).
-      command.executable = command.executable.replaceAll('/', '\\');
-    }
     process = Process.start(command.executable, command.arguments);
     process.onExit = exitHandler;
     process.onError = (e) {
       print("Error starting process:");
       print("  Command: $command");
       print("  Error: $e");
     };
     InputStream stdoutStream = process.stdout;
     InputStream stderrStream = process.stderr;
     StringInputStream stdoutStringStream = new StringInputStream(stdoutStream);
@@ skipping 553 matching lines @@
         // the developer doesn't waste his or her time trying to fix a bunch of
         // tests that appear to be broken but were actually just flakes that
         // didn't get retried because there had already been one failure.
         bool allowRetry = _MAX_FAILED_NO_RETRY > _progress.numFailedTests;
         new RunningProcess(test, allowRetry, this).start();
       }
       _numProcesses++;
     }
   }
 }