Fix error reporting on invalid command line args.

utils/tests/pub/test_pub.dart

Index: utils/tests/pub/test_pub.dart
diff --git a/utils/tests/pub/test_pub.dart b/utils/tests/pub/test_pub.dart
index 0c06a418f0ed72080d73016a656cb1116f330bf1..590c92b13798e8171ef8f29cdb6ef2737cebcd45 100644
--- a/utils/tests/pub/test_pub.dart
+++ b/utils/tests/pub/test_pub.dart
@@ -720,26 +720,26 @@ abstract class Descriptor {
    * Creates the file or directory within [dir]. Returns a [Future] that is
    * completed after the creation is done.
    */
-  abstract Future create(dir);
+  Future create(dir);
 
   /**
    * Validates that this descriptor correctly matches the corresponding file
    * system entry within [dir]. Returns a [Future] that completes to `null` if
    * the entry is valid, or throws an error if it failed.
    */
-  abstract Future validate(String dir);
+  Future validate(String dir);
 
   /**
    * Deletes the file or directory within [dir]. Returns a [Future] that is
    * completed after the deletion is done.
    */
-  abstract Future delete(String dir);
+  Future delete(String dir);
 
   /**
    * Loads the file at [path] from within this descriptor. If [path] is empty,
    * loads the contents of the descriptor itself.
    */
-  abstract InputStream load(List<String> path);
+  InputStream load(List<String> path);
 
   /**
    * Schedules the directory to be created before Pub is run with [runPub]. The
@@ -1159,7 +1159,7 @@ class TarFileDescriptor extends Descriptor {
       var sourceStream = tar.openInputStream();
       pipeInputToInput(sourceStream,
                        sinkStream,
-                       () => tempDir.delete(recursive: true));
+                       () => tempDir.deleteRecursively());
     });
     return sinkStream;
   }