Simplify CommandOutput and friends.

tools/testing/dart/command.dart

Index: tools/testing/dart/command.dart
diff --git a/tools/testing/dart/command.dart b/tools/testing/dart/command.dart
index 585f742971c5c63dd6bac3227a8bb546b0242fe6..e2b50b2e733cc0dceed0615b6357bfa4a7741dac 100644
--- a/tools/testing/dart/command.dart
+++ b/tools/testing/dart/command.dart
@@ -237,25 +237,18 @@ class CompilationCommand extends ProcessCommand {
   bool get outputIsUpToDate {
     if (_alwaysCompile) return false;
 
-    List<Uri> readDepsFile(String path) {
-      var file = new io.File(new Path(path).toNativePath());
-      if (!file.existsSync()) return null;
-
-      var lines = file.readAsLinesSync();
-      var dependencies = <Uri>[];
-      for (var line in lines) {
-        line = line.trim();
-        if (line.isNotEmpty) {
-          dependencies.add(Uri.parse(line));
-        }
+    var file = new io.File(new Path("$_outputFile.deps").toNativePath());
+    if (!file.existsSync()) return false;
+
+    var lines = file.readAsLinesSync();
+    var dependencies = <Uri>[];
+    for (var line in lines) {
+      line = line.trim();
+      if (line.isNotEmpty) {
+        dependencies.add(Uri.parse(line));
       }
-
-      return dependencies;
     }
 
-    var dependencies = readDepsFile("$_outputFile.deps");
-    if (dependencies == null) return false;
-
     dependencies.addAll(_bootstrapDependencies);
     var jsOutputLastModified = TestUtils.lastModifiedCache
         .getLastModified(new Uri(scheme: 'file', path: _outputFile));
@@ -512,7 +505,7 @@ class PubCommand extends ProcessCommand {
 abstract class ScriptCommand extends Command {
   ScriptCommand._(String displayName) : super._(displayName);
 
-  Future<ScriptCommandOutputImpl> run();
+  Future<ScriptCommandOutput> run();
 }
 
 class CleanDirectoryCopyCommand extends ScriptCommand {
@@ -525,7 +518,7 @@ class CleanDirectoryCopyCommand extends ScriptCommand {
   String get reproductionCommand =>
       "Copying '$_sourceDirectory' to '$_destinationDirectory'.";
 
-  Future<ScriptCommandOutputImpl> run() {
+  Future<ScriptCommandOutput> run() {
     var watch = new Stopwatch()..start();
 
     var destination = new io.Directory(_destinationDirectory);
@@ -541,10 +534,9 @@ class CleanDirectoryCopyCommand extends ScriptCommand {
         return TestUtils.copyDirectory(_sourceDirectory, _destinationDirectory);
       });
     }).then((_) {
-      return new ScriptCommandOutputImpl(
-          this, Expectation.pass, "", watch.elapsed);
+      return new ScriptCommandOutput(this, Expectation.pass, "", watch.elapsed);
     }).catchError((error) {
-      return new ScriptCommandOutputImpl(
+      return new ScriptCommandOutput(
           this, Expectation.fail, "An error occured: $error.", watch.elapsed);
     });
   }
@@ -571,7 +563,7 @@ class MakeSymlinkCommand extends ScriptCommand {
   String get reproductionCommand =>
       "Make symbolic link '$_link' (target: $_target)'.";
 
-  Future<ScriptCommandOutputImpl> run() {
+  Future<ScriptCommandOutput> run() {
     var watch = new Stopwatch()..start();
     var targetFile = new io.Directory(_target);
     return targetFile.exists().then((bool targetExists) {
@@ -584,10 +576,9 @@ class MakeSymlinkCommand extends ScriptCommand {
         if (exists) return link.delete();
       }).then((_) => link.create(_target));
     }).then((_) {
-      return new ScriptCommandOutputImpl(
-          this, Expectation.pass, "", watch.elapsed);
+      return new ScriptCommandOutput(this, Expectation.pass, "", watch.elapsed);
     }).catchError((error) {
-      return new ScriptCommandOutputImpl(
+      return new ScriptCommandOutput(
           this, Expectation.fail, "An error occured: $error.", watch.elapsed);
     });
   }