diff --git a/sdk/lib/_internal/js_shared/lib/rti.dart b/sdk/lib/_internal/js_shared/lib/rti.dart
index e9aa7efa028..9db2dfd049c 100644
--- a/sdk/lib/_internal/js_shared/lib/rti.dart
+++ b/sdk/lib/_internal/js_shared/lib/rti.dart
@@ -18,7 +18,7 @@ import 'dart:_foreign_helper'
         RAW_DART_FUNCTION_REF,
         TYPE_REF;
 import 'dart:_interceptors'
-    show JavaScriptFunction, JSArray, JSNull, JSUnmodifiableArray, JSObject;
+    show JavaScriptFunction, JSArray, JSNull, JSUnmodifiableArray;
 import 'dart:_js_helper'
     as records
     show createRecordTypePredicate, getRtiForRecord;
@@ -1303,8 +1303,6 @@ Object? _simpleSpecializedIsTest(Rti testRti) {
     isFn = RAW_DART_FUNCTION_REF(_isString);
   } else if (_Utils.isIdentical(testRti, TYPE_REF<bool>())) {
     isFn = RAW_DART_FUNCTION_REF(_isBool);
-  } else if (_Utils.isIdentical(testRti, TYPE_REF<JSObject>())) {
-    isFn = RAW_DART_FUNCTION_REF(_isJSObject);
   }
   return isFn;
 }
@@ -1675,24 +1673,6 @@ String? _asStringQ(dynamic object) {
   throw _TypeError.forType(object, 'String?');
 }
 
-bool _isJSObject(Object? object) {
-  if (object == null) return false;
-  if (JS('bool', 'typeof # == "object"', object)) {
-    if (_isDartObject(object)) return false;
-    return true;
-  }
-  if (JS('bool', 'typeof # == "function"', object)) {
-    if (JS_GET_FLAG('DEV_COMPILER')) {
-      // DDC functions have a signature attached.
-      var signatureName = JS_GET_NAME(JsGetName.SIGNATURE_NAME);
-      var signature = JS('', '#[#]', object, signatureName);
-      return signature == null;
-    }
-    return true;
-  }
-  return false;
-}
-
 String _rtiArrayToString(Object? array, List<String>? genericContext) {
   String s = '', sep = '';
   for (int i = 0; i < _Utils.arrayLength(array); i++) {