A class that's only used as a field type should be considered used

pkg/analyzer/lib/src/generated/resolver.dart

Index: pkg/analyzer/lib/src/generated/resolver.dart
diff --git a/pkg/analyzer/lib/src/generated/resolver.dart b/pkg/analyzer/lib/src/generated/resolver.dart
index b221f9ffb3ab9d4004f5d0fc08f51845b8b13a4e..a9c8edb48357aef9e0a681a0409fdcd7f43581b1 100644
--- a/pkg/analyzer/lib/src/generated/resolver.dart
+++ b/pkg/analyzer/lib/src/generated/resolver.dart
@@ -4922,7 +4922,10 @@ class GatherUsedLocalElementsVisitor extends RecursiveAstVisitor {
           return;
         }
         if (parent2 is VariableDeclarationList) {
-          return;
+          // If it's a field's type, it still counts as used.
+          if (parent2.parent is! FieldDeclaration) {
+            return;
+          }
         }
       }
     }