Dartdoc comments retrieved as metadata through dart2js mirrors.

tests/compiler/dart2js/mirrors_test.dart

Index: tests/compiler/dart2js/mirrors_test.dart
diff --git a/tests/compiler/dart2js/mirrors_test.dart b/tests/compiler/dart2js/mirrors_test.dart
index d80fc9fb709431acf3eb6d4e3a602ec20b3871a4..4c17a49397598e3be5d63a94b3bc256d463a5f75 100644
--- a/tests/compiler/dart2js/mirrors_test.dart
+++ b/tests/compiler/dart2js/mirrors_test.dart
@@ -38,7 +38,8 @@ main() {
   var dirPath = scriptPath.directoryPath;
   var libPath = dirPath.join(new Path.fromNative('../../../sdk/'));
   var inputPath = dirPath.join(new Path.fromNative('mirrors_helper.dart'));
-  var compilation = new Compilation.library([inputPath], libPath);
+  var compilation = new Compilation.library([inputPath], libPath, null,
+      <String>['--preserve-comments']);
   Expect.isNotNull(compilation, "No compilation created");
 
   var mirrors = compilation.mirrors;