Update rasta outline expectations.

pkg/front_end/test/fasta/rasta/native_is_illegal.dart.outline.expect

 library;
 import self as self;
 import "dart:core" as core;
 
 class Bar extends core::Object {
   get x() → self::Bar
-    return "Bar_get_x";
+    ;
   set x(self::Bar value) → dynamic
-    return "Bar_set_x";
+    ;
   method f() → dynamic
-    return "Bar_f";
+    ;
   static factory •() → self::Bar
-    return "Bar_constructor";
+    ;
 }
 static method foo() → dynamic
-  invalid-statement;
+  ;