Fine. Make LibraryElementImpl.fieldNameNonPromotabilityInfo @trackedDirectlyOpaque

I don't expect that it is used for any other library than the one we are
resolving. So, recorded opaque API usage will be ignored.

Change-Id: Id914e9eb498b769bbffe1cc77a1d118bb8d36c17
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/449923
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Paul Berry <paulberry@google.com>

pkg/analyzer/lib/src/dart/element/element.dart

@@ -6171,8 +6171,13 @@ class LibraryElementImpl extends ElementImpl
   ///
   /// If a field in the library has a private name and that name does not appear
   /// as a key in this map, the field is promotable.
+  @trackedDirectlyOpaque
   Map<String, FieldNameNonPromotabilityInfo> get fieldNameNonPromotabilityInfo {
     _ensureReadResolution();
+    globalResultRequirements?.recordOpaqueApiUse(
+      this,
+      'fieldNameNonPromotabilityInfo',
+    );
     return _fieldNameNonPromotabilityInfo!;
   }