tools/testing: move code into individual libraries

tools/testing/dart/multitest.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 multitest;
 
 import "dart:async";
 import "dart:io";
+
+import "path.dart";
 import "test_suite.dart";
 import "utils.dart";
 
 // Multitests are Dart test scripts containing lines of the form
 // " [some dart code] /// [key]: [error type]"
 //
 // For each key in the file, a new test file is made containing all
 // the normal lines of the file, and all of the multitest lines containing
 // that key, in the same order as in the source file.  The new test is expected
 // to pass if the error type listed is 'ok', or to fail if there is an error
@@ skipping 277 matching lines @@
     // TestSuite.forDirectory.
     split.removeLast();
   }
   String path = '${generatedTestDir.path}/${split.last}';
   Directory dir = new Directory(path);
   if (!dir.existsSync()) {
     dir.createSync();
   }
   return new Path(new File(path).absolute.path);
 }