Handle resolvedAst for forwarding constructors and callType on unnamed mixin applications.

tests/compiler/dart2js/parser_test.dart

Index: tests/compiler/dart2js/parser_test.dart
diff --git a/tests/compiler/dart2js/parser_test.dart b/tests/compiler/dart2js/parser_test.dart
index 2ee3d9e729cd2d0c2a6796c5f55af5b2ddf15616..762d07417b9f82a026122bcf169f1bb940ceb18b 100644
--- a/tests/compiler/dart2js/parser_test.dart
+++ b/tests/compiler/dart2js/parser_test.dart
@@ -319,7 +319,8 @@ class Collector extends DiagnosticReporter {
   }
 
   @override
-  DiagnosticMessage createMessage(spannable, messageKind, [arguments]) {
+  DiagnosticMessage createMessage(
+      spannable, messageKind, [arguments = const {}]) {
     return new DiagnosticMessage(null, spannable, null);
   }
 }