Use unit featureSet during linking.

This fixes NonNullOptOutTest.test_nnbd_optOut_late with summary2.

R=brianwilkerson@google.com

Change-Id: I9939ca92daaed349491df3463394164ead5d626b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/106205
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
diff --git a/pkg/analyzer/lib/src/summary2/builder/source_library_builder.dart b/pkg/analyzer/lib/src/summary2/builder/source_library_builder.dart
index 2845328..22fb71ee57 100644
--- a/pkg/analyzer/lib/src/summary2/builder/source_library_builder.dart
+++ b/pkg/analyzer/lib/src/summary2/builder/source_library_builder.dart
@@ -247,7 +247,7 @@
         linker.elementFactory,
         element,
         unitReference,
-        linker.contextFeatures.isEnabled(Feature.non_nullable),
+        unitContext.unit.featureSet.isEnabled(Feature.non_nullable),
         scope,
       );
       unitContext.unit.accept(resolver);
diff --git a/pkg/analyzer/lib/src/summary2/link.dart b/pkg/analyzer/lib/src/summary2/link.dart
index f9f3ce7..bc3b18f 100644
--- a/pkg/analyzer/lib/src/summary2/link.dart
+++ b/pkg/analyzer/lib/src/summary2/link.dart
@@ -63,10 +63,6 @@
     return elementFactory.analysisContext;
   }
 
-  FeatureSet get contextFeatures {
-    return analysisContext.analysisOptions.contextFeatures;
-  }
-
   DeclaredVariables get declaredVariables {
     return analysisContext.declaredVariables;
   }