// Copyright 2017 the V8 project authors. All rights reserved.// Use of this source code is governed by a BSD-style license that can be// found in the LICENSE file.// Flags: --allow-natives-syntaxfunctionTestBuiltinSubclassing(Builtin){assertTrue(%HasFastProperties(Builtin));assertTrue(%HasFastProperties(Builtin.prototype));assertTrue(%HasFastProperties(Builtin.prototype.__proto__));classSubClassextendsBuiltin{}assertTrue(%HasFastProperties(Builtin));assertTrue(%HasFastProperties(Builtin.prototype));assertTrue(%HasFastProperties(Builtin.prototype.__proto__));}letTypedArray=Uint8Array.__proto__;TestBuiltinSubclassing(RegExp);TestBuiltinSubclassing(Promise);TestBuiltinSubclassing(Array);TestBuiltinSubclassing(TypedArray);TestBuiltinSubclassing(Uint8Array);TestBuiltinSubclassing(Int8Array);TestBuiltinSubclassing(Uint16Array);TestBuiltinSubclassing(Int16Array);TestBuiltinSubclassing(Uint32Array);TestBuiltinSubclassing(Int32Array);TestBuiltinSubclassing(Float32Array);TestBuiltinSubclassing(Float64Array);TestBuiltinSubclassing(Uint8ClampedArray);