1 files changed, 20 insertions, 0 deletions
diff --git a/deps/v8/test/mjsunit/es9/regress/regress-866229.js b/deps/v8/test/mjsunit/es9/regress/regress-866229.js
new file mode 100644
index 00000000000..7e98c6ae8af
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+++ b/deps/v8/test/mjsunit/es9/regress/regress-866229.js
@@ -0,0 +1,20 @@
+// Copyright 2018 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-syntax
+
+var obj = { length: 1, 0: "spread" };
+obj[Symbol.toStringTag] = "foo";
+obj[Symbol.hasInstance] = function() { return true; }
+obj[Symbol.isConcatSpreadable] = true;
+
+var obj2 = { ...obj };
+
+// Crash if fast result map bitfield is not set correctly, if verifying heap
+%HeapObjectVerify(obj2);
+
+// Ensure correct result for some well-known symbols
+assertEquals("[object foo]", Object.prototype.toString.call(obj2));
+assertTrue(Uint8Array instanceof obj2);
+assertEquals(["spread"], [].concat(obj2));