Make catch variables final.

pkg/front_end/test/fasta/expressions.dart.direct.expect

Index: pkg/front_end/test/fasta/expressions.dart.direct.expect
diff --git a/pkg/front_end/test/fasta/expressions.dart.direct.expect b/pkg/front_end/test/fasta/expressions.dart.direct.expect
index fde709d0c0c518d1883da6a13892bf6250eb6964..6b5a4195b480b4c29e948ef03f6ad6e08f9cb88a 100644
--- a/pkg/front_end/test/fasta/expressions.dart.direct.expect
+++ b/pkg/front_end/test/fasta/expressions.dart.direct.expect
@@ -21,7 +21,7 @@ static method main() → dynamic {
   try {
     throw "fisk";
   }
-  on core::String catch(dynamic e, dynamic s) {
+  on core::String catch(final dynamic e, final dynamic s) {
     core::print(e);
     if(!s.==(null))
       core::print(s);
@@ -72,7 +72,7 @@ static method main() → dynamic {
     core::print(throw new core::NoSuchMethodError::•(null, #toString, <dynamic>[], <dynamic, dynamic>{}, null));
     throw "Shouldn't work";
   }
-  on core::NoSuchMethodError catch(dynamic e) {
+  on core::NoSuchMethodError catch(final dynamic e) {
     core::print("As expected: ${e}");
   }
   core::print(core::int::parse("42"));