Simplify _InvalidAccessVerifier._hasTypeOrSuperType().

R=brianwilkerson@google.com

Change-Id: I4855170939bf8dc89afdc3dd4d7a91c4819e5667
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/153948
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

Author: scheglov

pkg/analyzer/lib/src/error/best_practices_verifier.dart

@@ -1609,18 +1609,7 @@ class _InvalidAccessVerifier {
     if (element == null) {
       return false;
     }
-    if (element == superElement) {
-      return true;
-    }
-    // TODO(scheglov) `allSupertypes` is very expensive
-    var allSupertypes = element.allSupertypes;
-    for (var i = 0; i < allSupertypes.length; i++) {
-      var supertype = allSupertypes[i];
-      if (supertype.element == superElement) {
-        return true;
-      }
-    }
-    return false;
+    return element.thisType.asInstanceOf(superElement) != null;
   }
 
   bool _hasVisibleForTemplate(Element element) {