diff --git a/test/mjsunit/es6/proxies-json.js b/test/mjsunit/es6/proxies-json.js
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@@ -0,0 +1,505 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+
+///////////////////////////////////////////////////////////////////////////////
+// JSON.stringify
+
+
+function testStringify(expected, object) {
+  // Test fast case that bails out to slow case.
+  assertEquals(expected, JSON.stringify(object));
+  // Test slow case.
+  assertEquals(expected, JSON.stringify(object, undefined, 0));
+}
+
+
+// Test serializing a proxy, a function proxy, and objects that contain them.
+
+var handler1 = {
+  get: function(target, name) {
+    return name.toUpperCase();
+  },
+  ownKeys: function() {
+    return ['a', 'b', 'c'];
+  },
+  getOwnPropertyDescriptor: function() {
+    return { enumerable: true, configurable: true };
+  }
+}
+
+var proxy1 = new Proxy({}, handler1);
+testStringify('{"a":"A","b":"B","c":"C"}', proxy1);
+
+var proxy_fun = new Proxy(() => {}, handler1);
+assertTrue(typeof(proxy_fun) === 'function');
+testStringify(undefined, proxy_fun);
+testStringify('[1,null]', [1, proxy_fun]);
+
+handler1.apply = function() { return 666; };
+testStringify(undefined, proxy_fun);
+testStringify('[1,null]', [1, proxy_fun]);
+
+var parent1a = { b: proxy1 };
+testStringify('{"b":{"a":"A","b":"B","c":"C"}}', parent1a);
+
+var parent1b = { a: 123, b: proxy1, c: true };
+testStringify('{"a":123,"b":{"a":"A","b":"B","c":"C"},"c":true}', parent1b);
+
+var parent1c = [123, proxy1, true];
+testStringify('[123,{"a":"A","b":"B","c":"C"},true]', parent1c);
+
+
+// Proxy with side effect.
+
+var handler2 = {
+  get: function(target, name) {
+    delete parent2.c;
+    return name.toUpperCase();
+  },
+  ownKeys: function() {
+    return ['a', 'b', 'c'];
+  },
+  getOwnPropertyDescriptor: function() {
+    return { enumerable: true, configurable: true };
+  }
+}
+
+var proxy2 = new Proxy({}, handler2);
+var parent2 = { a: "delete", b: proxy2, c: "remove" };
+var expected2 = '{"a":"delete","b":{"a":"A","b":"B","c":"C"}}';
+assertEquals(expected2, JSON.stringify(parent2));
+parent2.c = "remove";  // Revert side effect.
+assertEquals(expected2, JSON.stringify(parent2, undefined, 0));
+
+
+// Proxy with a get function that uses the receiver argument.
+
+var handler3 = {
+  get: function(target, name, receiver) {
+    if (name == 'valueOf' || name === Symbol.toPrimitive) {
+      return function() { return "proxy" };
+    };
+    if (typeof name !== 'symbol') return name + "(" + receiver + ")";
+  },
+  ownKeys: function() {
+    return ['a', 'b', 'c'];
+  },
+  getOwnPropertyDescriptor: function() {
+    return { enumerable: true, configurable: true };
+  }
+}
+
+var proxy3 = new Proxy({}, handler3);
+var parent3 = { x: 123, y: proxy3 }
+testStringify('{"x":123,"y":{"a":"a(proxy)","b":"b(proxy)","c":"c(proxy)"}}',
+              parent3);
+
+
+// Empty proxy.
+
+var handler4 = {
+  get: function(target, name) {
+    return 0;
+  },
+  has: function() {
+    return true;
+  },
+  getOwnPropertyDescriptor: function(target, name) {
+    return { enumerable: false };
+  }
+}
+
+var proxy4 = new Proxy({}, handler4);
+testStringify('{}', proxy4);
+testStringify('{"a":{}}', { a: proxy4 });
+
+
+// Proxy that provides a toJSON function that uses this.
+
+var handler5 = {
+  get: function(target, name) {
+    if (name == 'z') return 97000;
+    return function(key) { return key.charCodeAt(0) + this.z; };
+  },
+  ownKeys: function(target) {
+    return ['toJSON', 'z'];
+  },
+  has: function() {
+    return true;
+  },
+  getOwnPropertyDescriptor: function(target, name) {
+    return { enumerable: true };
+  }
+}
+
+var proxy5 = new Proxy({}, handler5);
+testStringify('{"a":97097}', { a: proxy5 });
+
+
+// Proxy that provides a toJSON function that returns undefined.
+
+var handler6 = {
+  get: function(target, name) {
+    return function(key) { return undefined; };
+  },
+  ownKeys: function(target) {
+    return ['toJSON'];
+  },
+  has: function() {
+    return true;
+  },
+  getOwnPropertyDescriptor: function(target, name) {
+    return { enumerable: true };
+  }
+}
+
+var proxy6 = new Proxy({}, handler6);
+testStringify('[1,null,true]', [1, proxy6, true]);
+testStringify('{"a":1,"c":true}', {a: 1, b: proxy6, c: true});
+
+
+// Object containing a proxy that changes the parent's properties.
+
+var handler7 = {
+  get: function(target, name) {
+    delete parent7.a;
+    delete parent7.c;
+    parent7.e = "5";
+    return name.toUpperCase();
+  },
+  ownKeys: function() {
+    return ['a', 'b', 'c'];
+  },
+  getOwnPropertyDescriptor: function() {
+    return { enumerable: true, configurable: true };
+  }
+}
+
+var proxy7 = new Proxy({}, handler7);
+var parent7 = { a: "1", b: proxy7, c: "3", d: "4" };
+assertEquals('{"a":"1","b":{"a":"A","b":"B","c":"C"},"d":"4"}',
+             JSON.stringify(parent7));
+assertEquals('{"b":{"a":"A","b":"B","c":"C"},"d":"4","e":"5"}',
+             JSON.stringify(parent7));
+
+
+// (Proxy handler to log trap calls)
+
+var log = [];
+var logger = {};
+var handler = new Proxy({}, logger);
+
+logger.get = function(t, trap, r) {
+  return function() {
+    log.push([trap, ...arguments]);
+    return Reflect[trap](...arguments);
+  }
+};
+
+
+// Object is a callable proxy
+
+log.length = 0;
+var target = () => 42;
+var proxy = new Proxy(target, handler);
+assertTrue(typeof proxy === 'function');
+
+assertEquals(undefined, JSON.stringify(proxy));
+assertEquals(1, log.length)
+for (var i in log) assertSame(target, log[i][1]);
+
+assertEquals(["get", target, "toJSON", proxy], log[0]);
+
+
+// Object is a non-callable non-arraylike proxy
+
+log.length = 0;
+var target = {foo: 42}
+var proxy = new Proxy(target, handler);
+assertFalse(Array.isArray(proxy));
+
+assertEquals('{"foo":42}', JSON.stringify(proxy));
+assertEquals(4, log.length)
+for (var i in log) assertSame(target, log[i][1]);
+
+assertEquals(
+    ["get", target, "toJSON", proxy], log[0]);
+assertEquals(
+    ["ownKeys", target], log[1]);  // EnumerableOwnNames
+assertEquals(
+    ["getOwnPropertyDescriptor", target, "foo"], log[2]);  // EnumerableOwnNames
+assertEquals(
+    ["get", target, "foo", proxy], log[3]);
+
+
+// Object is an arraylike proxy
+
+log.length = 0;
+var target = [42];
+var proxy = new Proxy(target, handler);
+assertTrue(Array.isArray(proxy));
+
+assertEquals('[42]', JSON.stringify(proxy));
+assertEquals(3, log.length)
+for (var i in log) assertSame(target, log[i][1]);
+
+assertEquals(["get", target, "toJSON", proxy], log[0]);
+assertEquals(["get", target, "length", proxy], log[1]);
+assertEquals(["get", target, "0", proxy], log[2]);
+
+
+// Replacer is a callable proxy
+
+log.length = 0;
+var object = {0: "foo", 1: 666};
+var target = (key, val) => key == "1" ? val + 42 : val;
+var proxy = new Proxy(target, handler);
+assertTrue(typeof proxy === 'function');
+
+assertEquals('{"0":"foo","1":708}', JSON.stringify(object, proxy));
+assertEquals(3, log.length)
+for (var i in log) assertSame(target, log[i][1]);
+
+assertEquals(4, log[0].length)
+assertEquals("apply", log[0][0]);
+assertEquals("", log[0][3][0]);
+assertEquals({0: "foo", 1: 666}, log[0][3][1]);
+assertEquals(4, log[1].length)
+assertEquals("apply", log[1][0]);
+assertEquals(["0", "foo"], log[1][3]);
+assertEquals(4, log[2].length)
+assertEquals("apply", log[2][0]);
+assertEquals(["1", 666], log[2][3]);
+
+
+// Replacer is an arraylike proxy
+
+log.length = 0;
+var object = {0: "foo", 1: 666};
+var target = [0];
+var proxy = new Proxy(target, handler);
+assertTrue(Array.isArray(proxy));
+
+assertEquals('{"0":"foo"}', JSON.stringify(object, proxy));
+assertEquals(2, log.length)
+for (var i in log) assertSame(target, log[i][1]);
+
+assertEquals(["get", target, "length", proxy], log[0]);
+assertEquals(["get", target, "0", proxy], log[1]);
+
+
+// Replacer is an arraylike proxy and object is an array
+
+log.length = 0;
+var object = ["foo", 42];
+var target = [0];
+var proxy = new Proxy(target, handler);
+assertTrue(Array.isArray(proxy));
+
+assertEquals('["foo",42]', JSON.stringify(object, proxy));
+assertEquals(2, log.length);
+for (var i in log) assertSame(target, log[i][1]);
+
+assertEquals(["get", target, "length", proxy], log[0]);
+assertEquals(["get", target, "0", proxy], log[1]);
+
+
+// Replacer is an arraylike proxy with a non-trivial length
+
+var getTrap = function(t, key) {
+  if (key === "length") return {[Symbol.toPrimitive]() {return 42}};
+  if (key === "41") return "foo";
+  if (key === "42") return "bar";
+};
+var target = [];
+var proxy = new Proxy(target, {get: getTrap});
+assertTrue(Array.isArray(proxy));
+var object = {foo: true, bar: 666};
+assertEquals('{"foo":true}', JSON.stringify(object, proxy));
+
+
+// Replacer is an arraylike proxy with a bogus length
+
+var getTrap = function(t, key) {
+  if (key === "length") return Symbol();
+  if (key === "41") return "foo";
+  if (key === "42") return "bar";
+};
+var target = [];
+var proxy = new Proxy(target, {get: getTrap});
+assertTrue(Array.isArray(proxy));
+var object = {foo: true, bar: 666};
+assertThrows(() => JSON.stringify(object, proxy), TypeError);
+
+
+// Replacer returns a non-callable non-arraylike proxy
+
+log.length = 0;
+var object = ["foo", 42];
+var target = {baz: 5};
+var proxy = new Proxy(target, handler);
+var replacer = (key, val) => key === "1" ? proxy : val;
+
+assertEquals('["foo",{"baz":5}]', JSON.stringify(object, replacer));
+assertEquals(3, log.length);
+for (var i in log) assertSame(target, log[i][1]);
+
+assertEquals(["ownKeys", target], log[0]);
+assertEquals(["getOwnPropertyDescriptor", target, "baz"], log[1]);
+
+
+// Replacer returns an arraylike proxy
+
+log.length = 0;
+var object = ["foo", 42];
+var target = ["bar"];
+var proxy = new Proxy(target, handler);
+var replacer = (key, val) => key === "1" ? proxy : val;
+
+assertEquals('["foo",["bar"]]', JSON.stringify(object, replacer));
+assertEquals(2, log.length);
+for (var i in log) assertSame(target, log[i][1]);
+
+assertEquals(["get", target, "length", proxy], log[0]);
+assertEquals(["get", target, "0", proxy], log[1]);
+
+
+// Replacer returns an arraylike proxy with a non-trivial length
+
+var getTrap = function(t, key) {
+  if (key === "length") return {[Symbol.toPrimitive]() {return 3}};
+  if (key === "2") return "baz";
+  if (key === "3") return "bar";
+};
+var target = [];
+var proxy = new Proxy(target, {get: getTrap});
+var replacer = (key, val) => key === "goo" ? proxy : val;
+var object = {foo: true, goo: false};
+assertEquals('{"foo":true,"goo":[null,null,"baz"]}',
+    JSON.stringify(object, replacer));
+
+
+// Replacer returns an arraylike proxy with a bogus length
+
+var getTrap = function(t, key) {
+  if (key === "length") return Symbol();
+  if (key === "2") return "baz";
+  if (key === "3") return "bar";
+};
+var target = [];
+var proxy = new Proxy(target, {get: getTrap});
+var replacer = (key, val) => key === "goo" ? proxy : val;
+var object = {foo: true, goo: false};
+assertThrows(() => JSON.stringify(object, replacer), TypeError);
+
+
+// Replacer returns a callable proxy
+
+log.length = 0;
+var target = () => 666;
+var proxy = new Proxy(target, handler);
+var replacer = (key, val) => key === "1" ? proxy : val;
+
+assertEquals('["foo",null]', JSON.stringify(["foo", 42], replacer));
+assertEquals(0, log.length);
+
+assertEquals('{"0":"foo"}', JSON.stringify({0: "foo", 1: 42}, replacer));
+assertEquals(0, log.length);
+
+
+
+///////////////////////////////////////////////////////////////////////////////
+// JSON.parse
+
+
+// Reviver is a callable proxy
+
+log.length = 0;
+var target = () => 42;
+var proxy = new Proxy(target, handler);
+assertTrue(typeof proxy === "function");
+
+assertEquals(42, JSON.parse("[true, false]", proxy));
+assertEquals(3, log.length);
+for (var i in log) assertSame(target, log[i][1]);
+
+assertEquals(4, log[0].length);
+assertEquals("apply", log[0][0]);
+assertEquals(["0", true], log[0][3]);
+assertEquals(4, log[1].length);
+assertEquals("apply", log[1][0]);
+assertEquals(["1", false], log[1][3]);
+assertEquals(4, log[2].length);
+assertEquals("apply", log[2][0]);
+assertEquals(["", [42, 42]], log[2][3]);
+
+
+// Reviver plants a non-arraylike proxy into a yet-to-be-visited property
+
+log.length = 0;
+var target = {baz: 42};
+var proxy = new Proxy(target, handler);
+var reviver = function(p, v) {
+  if (p === "baz") return 5;
+  if (p === "foo") this.bar = proxy;
+  return v;
+}
+
+assertEquals({foo: 0, bar: proxy}, JSON.parse('{"foo":0,"bar":1}', reviver));
+assertEquals(4, log.length);
+for (var i in log) assertSame(target, log[i][1]);
+
+assertEquals(["ownKeys", target], log[0]);
+assertEquals(["getOwnPropertyDescriptor", target, "baz"], log[1]);
+assertEquals(["get", target, "baz", proxy], log[2]);
+assertEquals(["defineProperty", target, "baz",
+    {value: 5, configurable: true, writable: true, enumerable: true}], log[3]);
+
+
+// Reviver plants an arraylike proxy into a yet-to-be-visited property
+
+log.length = 0;
+var target = [42];
+var proxy = new Proxy(target, handler);
+assertTrue(Array.isArray(proxy));
+var reviver = function(p, v) {
+  if (p === "0") return undefined;
+  if (p === "foo") this.bar = proxy;
+  return v;
+}
+
+var result = JSON.parse('{"foo":0,"bar":1}', reviver);
+assertEquals({foo: 0, bar: proxy}, result);
+assertSame(result.bar, proxy);
+assertEquals(3, log.length);
+for (var i in log) assertSame(target, log[i][1]);
+
+assertEquals(["get", target, "length", proxy], log[0]);
+assertEquals(["get", target, "0", proxy], log[1]);
+assertEquals(["deleteProperty", target, "0"], log[2]);