Enable conditional imports in unparser test.

tests/compiler/dart2js/parser_helper.dart

Index: tests/compiler/dart2js/parser_helper.dart
diff --git a/tests/compiler/dart2js/parser_helper.dart b/tests/compiler/dart2js/parser_helper.dart
index eeba1f9a6fd1086ae89e7bd471ebe77cbfc77ca7..202e6f20e17126d9c4934fabab00a164193e89bc 100644
--- a/tests/compiler/dart2js/parser_helper.dart
+++ b/tests/compiler/dart2js/parser_helper.dart
@@ -102,7 +102,7 @@ Node parseBodyCode(String text, Function parseMethod,
   NodeListener listener = new NodeListener(
       new ScannerOptions(canUseNative: true),
       reporter, library.entryCompilationUnit);
-  Parser parser = new Parser(listener);
+  Parser parser = new Parser(listener, enableConditionalDirectives: true);
   Token endToken = parseMethod(parser, tokens);
   assert(endToken.kind == EOF_TOKEN);
   Node node = listener.popNode();