Handle creating ParameterMirrors for the parameters of forwarding constructors.

tests/lib/mirrors/immutable_collections_test.dart

Index: tests/lib/mirrors/immutable_collections_test.dart
diff --git a/tests/lib/mirrors/immutable_collections_test.dart b/tests/lib/mirrors/immutable_collections_test.dart
index 93eafbdc59b0194c6830f1a318e35000bc22845c..7906fcaf3c7be4ceead9e71891c0829c7fd822e2 100644
--- a/tests/lib/mirrors/immutable_collections_test.dart
+++ b/tests/lib/mirrors/immutable_collections_test.dart
@@ -34,9 +34,9 @@ checkParameter(ParameterMirror pm) {
 }
 
 checkMethod(MethodMirror mm) {
+  print(mm);
   checkList(mm.parameters, 'MethodMirror.parameters');
   checkList(mm.metadata, 'MethodMirror.metadata');
-
   mm.parameters.forEach(checkParameter);
 }