[analyzer] Fix off-by-one-error in experiments

Change-Id: I5c9710c7e6ea737b68f8c694ba6cde1690b74d2a
Reviewed-on: https://dart-review.googlesource.com/c/92566
Auto-Submit: Mike Fairhurst <mfairhurst@google.com>
Reviewed-by: Paul Berry <paulberry@google.com>
diff --git a/pkg/analyzer/lib/src/dart/analysis/experiments.dart b/pkg/analyzer/lib/src/dart/analysis/experiments.dart
index 16d56a9..5bf37c7 100644
--- a/pkg/analyzer/lib/src/dart/analysis/experiments.dart
+++ b/pkg/analyzer/lib/src/dart/analysis/experiments.dart
@@ -120,7 +120,6 @@
       bool spread_collections})
       : _enableFlags = <bool>[
           constant_update_2018 ?? IsEnabledByDefault.constant_update_2018,
-          set_literals ?? IsEnabledByDefault.set_literals,
           non_nullable ?? IsEnabledByDefault.non_nullable,
           control_flow_collections ??
               IsEnabledByDefault.control_flow_collections,