Specifiy MethodMirror.isStatic is terms of whether 'this' is permitted.

runtime/lib/mirrors.cc

Index: runtime/lib/mirrors.cc
diff --git a/runtime/lib/mirrors.cc b/runtime/lib/mirrors.cc
index 463b3de856bcd4391cce27dc823b018a6f4a53c9..14308aa4a78e38a757e4442fd5351d165f1c63ae 100644
--- a/runtime/lib/mirrors.cc
+++ b/runtime/lib/mirrors.cc
@@ -246,7 +246,7 @@ static RawInstance* CreateMethodMirror(const Function& func,
   args.SetAt(1, name);
 
   args.SetAt(2, owner_mirror);
-  args.SetAt(3, Bool::Get(func.is_static()));
+  args.SetAt(3, Bool::Get(func.is_static() && !func.IsClosureFunction()));
   args.SetAt(4, Bool::Get(func.is_abstract()));
   args.SetAt(5, Bool::Get(func.IsGetterFunction()));
   args.SetAt(6, Bool::Get(func.IsSetterFunction()));