Switch to Fasta in "golden" tests of closure conversion

pkg/kernel/testcases/closures/named_closure.dart.expect

Index: pkg/kernel/testcases/closures/named_closure.dart.expect
diff --git a/pkg/kernel/testcases/closures/named_closure.dart.expect b/pkg/kernel/testcases/closures/named_closure.dart.expect
index d4358ffa9219cb1c22f64fe6d4965d6518557cc1..edc366675dd6cb921e7d0939cc121743bfcea4cd 100644
--- a/pkg/kernel/testcases/closures/named_closure.dart.expect
+++ b/pkg/kernel/testcases/closures/named_closure.dart.expect
@@ -2,14 +2,14 @@ library;
 import self as self;
 import "dart:core" as core;
 
-static field dynamic f = null;
+static field dynamic f;
 static method foo() → dynamic {
   core::print(self::f.call(0));
 }
 static method main(dynamic arguments) → dynamic {
   final Vector #context = MakeVector(2);
   #context[1] = arguments;
-  final (dynamic) → dynamic g = MakeClosure<(dynamic) → dynamic>(self::closure#main#g, #context);
+  final dynamic g = MakeClosure<(dynamic) → dynamic>(self::closure#main#g, #context);
   self::f = g;
   self::foo();
 }