Merge pull request dart-lang/clock#26 from dart-lang/pq-patch-1

remove redundant experiment

pkgs/clock/analysis_options.yaml

diff --git a/pkgs/clock/analysis_options.yaml b/pkgs/clock/analysis_options.yaml
index 237e493..168ac15 100644
--- a/pkgs/clock/analysis_options.yaml
+++ b/pkgs/clock/analysis_options.yaml
@@ -2,8 +2,6 @@
 analyzer:
   strong-mode:
     implicit-casts: false
-  enable-experiment:
-    - non-nullable
 linter:
   rules:
     - always_declare_return_types