fixes #25610, infer JS builtin in strong mode like we used to

pkg/analyzer/test/src/task/strong/inferred_type_test.dart

Index: pkg/analyzer/test/src/task/strong/inferred_type_test.dart
diff --git a/pkg/analyzer/test/src/task/strong/inferred_type_test.dart b/pkg/analyzer/test/src/task/strong/inferred_type_test.dart
index d823b20b49e2c3a02b3b4282a5d0c75c06a6e924..a397c9e9a609d6e85aaa3b9c4ba2374220d6658a 100644
--- a/pkg/analyzer/test/src/task/strong/inferred_type_test.dart
+++ b/pkg/analyzer/test/src/task/strong/inferred_type_test.dart
@@ -1583,5 +1583,21 @@ main() {
         }
     '''
     });
+
+    // TODO(jmesserly): we should change how this inference works.
+    // For now this test will cover what we use.
+    testChecker(
+        'infer from RHS only if it wont conflict with overridden fields 2', {
+      '/main.dart': '''
+        import 'dart:_foreign_helper' show JS;
+        main() {
+          String x = /*severe:STATIC_TYPE_ERROR*/JS('int', '42');
+          var y = JS('String', '"hello"');
+          y = "world";
+          y = /*severe:STATIC_TYPE_ERROR*/42;
+        }
+    '''
+    });
+
   });
 }