Re-triage mirror test failures on the analyzer.

tests/lib/mirrors/method_mirror_returntype_test.dart

Index: tests/lib/mirrors/method_mirror_returntype_test.dart
diff --git a/tests/lib/mirrors/method_mirror_returntype_test.dart b/tests/lib/mirrors/method_mirror_returntype_test.dart
index cd525bb174a07293760e178b1c88f9fd5abd19f6..be551562dce72b79c37e64386884e712b1e34713 100644
--- a/tests/lib/mirrors/method_mirror_returntype_test.dart
+++ b/tests/lib/mirrors/method_mirror_returntype_test.dart
@@ -21,20 +21,20 @@ class C<E> {
 main() {
   MethodMirror mm;
 
-  mm = reflect(intFunc).function;
+  mm = (reflect(intFunc) as ClosureMirror).function;
   Expect.equals(true, mm.returnType is TypeMirror);
   Expect.equals(#int, mm.returnType.simpleName);
   Expect.equals(true, mm.returnType.owner is LibraryMirror);
 
-  mm = reflect(dynamicFunc1).function;
+  mm = (reflect(dynamicFunc1) as ClosureMirror).function;
   Expect.equals(true, mm.returnType is TypeMirror);
   Expect.equals(#dynamic, mm.returnType.simpleName);
 
-  mm = reflect(dynamicFunc2).function;
+  mm = (reflect(dynamicFunc2) as ClosureMirror).function;
   Expect.equals(true, mm.returnType is TypeMirror);
   Expect.equals(#dynamic, mm.returnType.simpleName);
 
-  mm = reflect(voidFunc).function;
+  mm = (reflect(voidFunc) as ClosureMirror).function;
   Expect.equals(true, mm.returnType is TypeMirror);
   Expect.equals(const Symbol("void"), mm.returnType.simpleName);