fix completion after dot-keyword - fixes #23882

pkg/analysis_server/test/services/completion/prefixed_element_contributor_test.dart

Index: pkg/analysis_server/test/services/completion/prefixed_element_contributor_test.dart
diff --git a/pkg/analysis_server/test/services/completion/prefixed_element_contributor_test.dart b/pkg/analysis_server/test/services/completion/prefixed_element_contributor_test.dart
index 45f49034a3480de3c281989eb890f2c58bf42626..0126300c0d4f9a628c58025c241490d88b8f4756 100644
--- a/pkg/analysis_server/test/services/completion/prefixed_element_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/prefixed_element_contributor_test.dart
@@ -217,6 +217,13 @@ void f(C<int> c) {
     });
   }
 
+  test_keyword() {
+    addTestSource('class C { static C get instance => null; } main() {C.in^}');
+    return computeFull((bool result) {
+      assertSuggestGetter('instance', 'C');
+    });
+  }
+
   test_libraryPrefix() {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('import "dart:async" as bar; foo() {bar.^}');