Add support for not generating a .dill file.

lib/testing/rasta_chain.dart

Index: lib/testing/rasta_chain.dart
diff --git a/lib/testing/rasta_chain.dart b/lib/testing/rasta_chain.dart
index 74613e9b5fc91983f7daed5e0be3874b69a4b1ea..a717dc4368e20d5e2623477b3649eacc9ce497e4 100644
--- a/lib/testing/rasta_chain.dart
+++ b/lib/testing/rasta_chain.dart
@@ -14,12 +14,6 @@ import 'dart:io' show
 import 'package:kernel/ast.dart' show
     Program;
 
-import 'package:kernel/repository.dart' show
-    Repository;
-
-import 'package:kernel/binary/loader.dart' show
-    BinaryLoader;
-
 import 'package:testing/testing.dart' show
     ChainContext,
     Result,
@@ -55,11 +49,7 @@ abstract class RastaContext extends ChainContext {
 class RastaStep extends Step<TestDescription, Program, RastaContext> {
   final String prefix;
 
-  /// When true, return a copy of the program (by loading it from serialized
-  /// .dill file).
-  final bool reload;
-
-  const RastaStep(this.prefix, {this.reload: false});
+  const RastaStep(this.prefix);
 
   String get name => "rasta";
 
@@ -80,23 +70,14 @@ class RastaStep extends Step<TestDescription, Program, RastaContext> {
     Options options = new Options(
         source, dill, dependenciesFile: null,
         generateLibrary: false,
-        isVerbose: true, isBatch: false, pattern: null);
+        isVerbose: true, isBatch: false, pattern: null,
+        noOutput: task.globalOptions.noOutput);
 
-    Program program;
     try {
-      program = await task.runOne(options);
+      return pass(await task.runOne(options));
     } catch (e, t) {
       task.kernel.recoverFromCrash();
       return crash(e, t);
     }
-
-    if (reload) {
-      // TODO(ahe): We need to load the serialized form as we otherwise
-      // attempt to modify an unmodifiable list.
-      Repository repository = new Repository();
-      program = new BinaryLoader(repository).loadProgram(dill.toFilePath());
-    }
-
-    return pass(program);
   }
 }