Enable the "skip command compilation if output is already up-to-date" feature in dart2dart

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 33 matching lines @@
       executable = executable.replaceAll('/', '\\');
     }
     commandLine = "$executable ${Strings.join(arguments, ' ')}";
   }
 
   String toString() => commandLine;
 
   Future<bool> get outputIsUpToDate => new Future.immediate(false);
 }
 
-class Dart2JsCommand extends Command {
-  String _jsOutputFile;
+class CompilationCommand extends Command {
+  String _outputFile;
   bool _neverSkipCompilation;
   List<Uri> _bootstrapDependencies;
 
-  Dart2JsCommand(this._jsOutputFile,
-                 this._neverSkipCompilation,
-                 this._bootstrapDependencies,
-                 String executable,
-                 List<String> arguments)
+  CompilationCommand(this._outputFile,
+                     this._neverSkipCompilation,
+                     this._bootstrapDependencies,
+                     String executable,
+                     List<String> arguments)
       : super(executable, arguments);
 
   Future<bool> get outputIsUpToDate {
     if (_neverSkipCompilation) return new Future.immediate(false);
 
     Future<List<Uri>> readDepsFile(String path) {
       var file = new File(new Path(path).toNativePath());
       if (!file.existsSync()) {
         return new Future.immediate(null);
       }
       return file.readAsLines().transform((List<String> lines) {
         var dependencies = new List<Uri>();
         for (var line in lines) {
           line = line.trim();
           if (line.length > 0) {
             dependencies.add(new Uri(line));
           }
         }
         return dependencies;
       });
     }
 
-    return readDepsFile("$_jsOutputFile.deps").transform((dependencies) {
+    return readDepsFile("$_outputFile.deps").transform((dependencies) {
       if (dependencies != null) {
         dependencies.addAll(_bootstrapDependencies);
         var jsOutputLastModified = TestUtils.lastModifiedCache.getLastModified(
-            new Uri.fromComponents(scheme: 'file', path: _jsOutputFile));
+            new Uri.fromComponents(scheme: 'file', path: _outputFile));
         if (jsOutputLastModified != null) {
           for (var dependency in dependencies) {
             var dependencyLastModified =
                 TestUtils.lastModifiedCache.getLastModified(dependency);
             if (dependencyLastModified == null ||
                 dependencyLastModified > jsOutputLastModified) {
               return false;
             }
           }
           return true;
@@ skipping 1420 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++;
     }
   }
 }