Remove flags for ES2015 features shipped in M48

test/mjsunit/harmony/array-concat.js

-// Copyright 2014 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: --harmony-concat-spreadable --harmony-proxies --harmony-reflect
-
-(function testArrayConcatArity() {
-  "use strict";
-  assertEquals(1, Array.prototype.concat.length);
-})();
-
-
-(function testArrayConcatNoPrototype() {
-  "use strict";
-  assertEquals(void 0, Array.prototype.concat.prototype);
-})();
-
-
-(function testArrayConcatDescriptor() {
-  "use strict";
-  var desc = Object.getOwnPropertyDescriptor(Array.prototype, 'concat');
-  assertEquals(false, desc.enumerable);
-})();
-
-
-(function testConcatArrayLike() {
-  "use strict";
-  var obj = {
-    "length": 6,
-    "1": "A",
-    "3": "B",
-    "5": "C"
-  };
-  obj[Symbol.isConcatSpreadable] = true;
-  var obj2 = { length: 3, "0": "0", "1": "1", "2": "2" };
-  var arr = ["X", "Y", "Z"];
-  assertEquals([void 0, "A", void 0, "B", void 0, "C",
-               { "length": 3, "0": "0", "1": "1", "2": "2" },
-               "X", "Y", "Z"], Array.prototype.concat.call(obj, obj2, arr));
-})();
-
-
-(function testConcatArrayLikeStringLength() {
-  "use strict";
-  var obj = {
-    "length": "6",
-    "1": "A",
-    "3": "B",
-    "5": "C"
-  };
-  obj[Symbol.isConcatSpreadable] = true;
-  var obj2 = { length: 3, "0": "0", "1": "1", "2": "2" };
-  var arr = ["X", "Y", "Z"];
-  assertEquals([void 0, "A", void 0, "B", void 0, "C",
-               { "length": 3, "0": "0", "1": "1", "2": "2" },
-               "X", "Y", "Z"], Array.prototype.concat.call(obj, obj2, arr));
-})();
-
-
-(function testConcatArrayLikeNegativeLength() {
-  "use strict";
-  var obj = {
-    "length": -6,
-    "1": "A",
-    "3": "B",
-    "5": "C"
-  };
-  obj[Symbol.isConcatSpreadable] = true;
-  assertEquals([], [].concat(obj));
-  obj.length = -6.7;
-  assertEquals([], [].concat(obj));
-  obj.length = "-6";
-  assertEquals([], [].concat(obj));
-})();
-
-
-(function testConcatArrayLikeToLengthThrows() {
-  "use strict";
-  var obj = {
-    "length": {valueOf: null, toString: null},
-    "1": "A",
-    "3": "B",
-    "5": "C"
-  };
-  obj[Symbol.isConcatSpreadable] = true;
-  var obj2 = { length: 3, "0": "0", "1": "1", "2": "2" };
-  var arr = ["X", "Y", "Z"];
-  assertThrows(function() {
-    Array.prototype.concat.call(obj, obj2, arr);
-  }, TypeError);
-})();
-
-
-(function testConcatArrayLikePrimitiveNonNumberLength() {
-  "use strict";
-  var obj = {
-    "1": "A",
-    "3": "B",
-    "5": "C"
-  };
-  obj[Symbol.isConcatSpreadable] = true;
-  obj.length = {toString: function() { return "SIX"; }, valueOf: null };
-  assertEquals([], [].concat(obj));
-  obj.length = {toString: null, valueOf: function() { return "SIX"; } };
-  assertEquals([], [].concat(obj));
-})();
-
-
-(function testConcatArrayLikeLengthToStringThrows() {
-  "use strict";
-  function MyError() {}
-  var obj = {
-    "length": { toString: function() {
-        throw new MyError();
-      }, valueOf: null
-    },
-    "1": "A",
-    "3": "B",
-    "5": "C"
-  };
-  obj[Symbol.isConcatSpreadable] = true;
-  assertThrows(function() {
-    [].concat(obj);
-  }, MyError);
-})();
-
-
-(function testConcatArrayLikeLengthValueOfThrows() {
-  "use strict";
-  function MyError() {}
-  var obj = {
-    "length": { valueOf: function() {
-      throw new MyError();
-    }, toString: null
-  },
-  "1": "A",
-  "3": "B",
-  "5": "C"
-};
-obj[Symbol.isConcatSpreadable] = true;
-assertThrows(function() {
-  [].concat(obj);
-}, MyError);
-})();
-
-
-(function testConcatHoleyArray() {
-  "use strict";
-  var arr = [];
-  arr[4] = "Item 4";
-  arr[8] = "Item 8";
-  var arr2 = [".", "!", "?"];
-  assertEquals([void 0, void 0, void 0, void 0, "Item 4", void 0, void 0,
-                void 0, "Item 8", ".", "!", "?"], arr.concat(arr2));
-})();
-
-
-(function testIsConcatSpreadableGetterThrows() {
-  "use strict";
-  function MyError() {}
-  var obj = {};
-  Object.defineProperty(obj, Symbol.isConcatSpreadable, {
-    get: function() { throw new MyError(); }
-  });
-
-  assertThrows(function() {
-    [].concat(obj);
-  }, MyError);
-
-  assertThrows(function() {
-    Array.prototype.concat.call(obj, 1, 2, 3);
-  }, MyError);
-})();
-
-
-(function testConcatLengthThrows() {
-  "use strict";
-  function MyError() {}
-  var obj = {};
-  obj[Symbol.isConcatSpreadable] = true;
-  Object.defineProperty(obj, "length", {
-    get: function() { throw new MyError(); }
-  });
-
-  assertThrows(function() {
-    [].concat(obj);
-  }, MyError);
-
-  assertThrows(function() {
-    Array.prototype.concat.call(obj, 1, 2, 3);
-  }, MyError);
-})();
-
-
-(function testConcatArraySubclass() {
-  "use strict";
-  // If @@isConcatSpreadable is not used, the value of IsArray(O)
-  // is used to determine the spreadable property.
-  class A extends Array {}
-  var obj = [].concat(new A(1, 2, 3), new A(4, 5, 6), new A(7, 8, 9));
-  assertEquals(9, obj.length);
-  for (var i = 0; i < obj.length; ++i) {
-    assertEquals(i + 1, obj[i]);
-  }
-
-  // TODO(caitp): when concat is called on instances of classes which extend
-  // Array, they should:
-  //
-  // - return an instance of the class, rather than an Array instance (if from
-  //   same Realm)
-  // - always treat such classes as concat-spreadable
-})();
-
-
-(function testConcatArraySubclassOptOut() {
-  "use strict";
-  class A extends Array {
-    get [Symbol.isConcatSpreadable]() { return false; }
-  }
-  var obj = [].concat(new A(1, 2, 3), new A(4, 5, 6), new A(7, 8, 9));
-  assertEquals(3, obj.length);
-  assertEquals(3, obj[0].length);
-  assertEquals(3, obj[1].length);
-  assertEquals(3, obj[2].length);
-})();
-
-
-(function testConcatNonArray() {
-  "use strict";
-  class NonArray {
-    constructor() { Array.apply(this, arguments); }
-  };
-
-  var obj = new NonArray(1,2,3);
-  var result = Array.prototype.concat.call(obj, 4, 5, 6);
-  assertEquals(Array, result.constructor);
-  assertEquals([obj,4,5,6], result);
-  assertFalse(result instanceof NonArray);
-})();
-
-
-function testConcatTypedArray(type, elems, modulo) {
-  "use strict";
-  var items = new Array(elems);
-  var ta_by_len = new type(elems);
-  for (var i = 0; i < elems; ++i) {
-    ta_by_len[i] = items[i] = modulo === false ? i : elems % modulo;
-  }
-  var ta = new type(items);
-  assertEquals([ta, ta], [].concat(ta, ta));
-  ta[Symbol.isConcatSpreadable] = true;
-  assertEquals(items, [].concat(ta));
-
-  assertEquals([ta_by_len, ta_by_len], [].concat(ta_by_len, ta_by_len));
-  ta_by_len[Symbol.isConcatSpreadable] = true;
-  assertEquals(items, [].concat(ta_by_len));
-
-  // TypedArray with fake `length`.
-  ta = new type(1);
-  var defValue = ta[0];
-  var expected = new Array(4000);
-  expected[0] = defValue;
-
-  Object.defineProperty(ta, "length", { value: 4000 });
-  ta[Symbol.isConcatSpreadable] = true;
-  assertEquals(expected, [].concat(ta));
-}
-
-(function testConcatSmallTypedArray() {
-  var max = [Math.pow(2, 8), Math.pow(2, 16), Math.pow(2, 32), false, false];
-  [
-    Uint8Array,
-    Uint16Array,
-    Uint32Array,
-    Float32Array,
-    Float64Array
-  ].forEach(function(ctor, i) {
-    testConcatTypedArray(ctor, 1, max[i]);
-  });
-})();
-
-
-(function testConcatLargeTypedArray() {
-  var max = [Math.pow(2, 8), Math.pow(2, 16), Math.pow(2, 32), false, false];
-  [
-    Uint8Array,
-    Uint16Array,
-    Uint32Array,
-    Float32Array,
-    Float64Array
-  ].forEach(function(ctor, i) {
-    testConcatTypedArray(ctor, 4000, max[i]);
-  });
-})();
-
-
-(function testConcatStrictArguments() {
-  var args = (function(a, b, c) { "use strict"; return arguments; })(1,2,3);
-  args[Symbol.isConcatSpreadable] = true;
-  assertEquals([1, 2, 3, 1, 2, 3], [].concat(args, args));
-
-  Object.defineProperty(args, "length", { value: 6 });
-  assertEquals([1, 2, 3, void 0, void 0, void 0], [].concat(args));
-})();
-
-
-(function testConcatSloppyArguments() {
-  var args = (function(a, b, c) { return arguments; })(1,2,3);
-  args[Symbol.isConcatSpreadable] = true;
-  assertEquals([1, 2, 3, 1, 2, 3], [].concat(args, args));
-
-  Object.defineProperty(args, "length", { value: 6 });
-  assertEquals([1, 2, 3, void 0, void 0, void 0], [].concat(args));
-})();
-
-
-(function testConcatSloppyArgumentsWithDupes() {
-  var args = (function(a, a, a) { return arguments; })(1,2,3);
-  args[Symbol.isConcatSpreadable] = true;
-  assertEquals([1, 2, 3, 1, 2, 3], [].concat(args, args));
-
-  Object.defineProperty(args, "length", { value: 6 });
-  assertEquals([1, 2, 3, void 0, void 0, void 0], [].concat(args));
-})();
-
-
-(function testConcatSloppyArgumentsThrows() {
-  function MyError() {}
-  var args = (function(a) { return arguments; })(1,2,3);
-  Object.defineProperty(args, 0, {
-    get: function() { throw new MyError(); }
-  });
-  args[Symbol.isConcatSpreadable] = true;
-  assertThrows(function() {
-    return [].concat(args, args);
-  }, MyError);
-})();
-
-
-(function testConcatHoleySloppyArguments() {
-  var args = (function(a) { return arguments; })(1,2,3);
-  delete args[1];
-  args[Symbol.isConcatSpreadable] = true;
-  assertEquals([1, void 0, 3, 1, void 0, 3], [].concat(args, args));
-})();
-
-
-(function testConcatSpreadableStringWrapper() {
-  "use strict";
-  var str1 = new String("yuck\uD83D\uDCA9")
-  // String wrapper objects are not concat-spreadable by default
-  assertEquals([str1], [].concat(str1));
-
-  // String wrapper objects may be individually concat-spreadable
-  str1[Symbol.isConcatSpreadable] = true;
-  assertEquals(["y", "u", "c", "k", "\uD83D", "\uDCA9"],
-               [].concat(str1));
-
-  String.prototype[Symbol.isConcatSpreadable] = true;
-  // String wrapper objects may be concat-spreadable
-  assertEquals(["y", "u", "c", "k", "\uD83D", "\uDCA9"],
-               [].concat(new String("yuck\uD83D\uDCA9")));
-
-  // String values are never concat-spreadable
-  assertEquals(["yuck\uD83D\uDCA9"], [].concat("yuck\uD83D\uDCA9"));
-  delete String.prototype[Symbol.isConcatSpreadable];
-})();
-
-
-(function testConcatSpreadableBooleanWrapper() {
-  "use strict";
-  var bool = new Boolean(true)
-  // Boolean wrapper objects are not concat-spreadable by default
-  assertEquals([bool], [].concat(bool));
-
-  // Boolean wrapper objects may be individually concat-spreadable
-  bool[Symbol.isConcatSpreadable] = true;
-  bool.length = 3;
-  bool[0] = 1, bool[1] = 2, bool[2] = 3;
-  assertEquals([1, 2, 3], [].concat(bool));
-
-  Boolean.prototype[Symbol.isConcatSpreadable] = true;
-  // Boolean wrapper objects may be concat-spreadable
-  assertEquals([], [].concat(new Boolean(true)));
-  Boolean.prototype[0] = 1;
-  Boolean.prototype[1] = 2;
-  Boolean.prototype[2] = 3;
-  Boolean.prototype.length = 3;
-  assertEquals([1,2,3], [].concat(new Boolean(true)));
-
-  // Boolean values are never concat-spreadable
-  assertEquals([true], [].concat(true));
-  delete Boolean.prototype[Symbol.isConcatSpreadable];
-  delete Boolean.prototype[0];
-  delete Boolean.prototype[1];
-  delete Boolean.prototype[2];
-  delete Boolean.prototype.length;
-})();
-
-
-(function testConcatSpreadableNumberWrapper() {
-  "use strict";
-  var num = new Number(true)
-  // Number wrapper objects are not concat-spreadable by default
-  assertEquals([num], [].concat(num));
-
-  // Number wrapper objects may be individually concat-spreadable
-  num[Symbol.isConcatSpreadable] = true;
-  num.length = 3;
-  num[0] = 1, num[1] = 2, num[2] = 3;
-  assertEquals([1, 2, 3], [].concat(num));
-
-  Number.prototype[Symbol.isConcatSpreadable] = true;
-  // Number wrapper objects may be concat-spreadable
-  assertEquals([], [].concat(new Number(123)));
-  Number.prototype[0] = 1;
-  Number.prototype[1] = 2;
-  Number.prototype[2] = 3;
-  Number.prototype.length = 3;
-  assertEquals([1,2,3], [].concat(new Number(123)));
-
-  // Number values are never concat-spreadable
-  assertEquals([true], [].concat(true));
-  delete Number.prototype[Symbol.isConcatSpreadable];
-  delete Number.prototype[0];
-  delete Number.prototype[1];
-  delete Number.prototype[2];
-  delete Number.prototype.length;
-})();
-
-
-(function testConcatSpreadableFunction() {
-  "use strict";
-  var fn = function(a, b, c) {}
-  // Functions are not concat-spreadable by default
-  assertEquals([fn], [].concat(fn));
-
-  // Functions may be individually concat-spreadable
-  fn[Symbol.isConcatSpreadable] = true;
-  fn[0] = 1, fn[1] = 2, fn[2] = 3;
-  assertEquals([1, 2, 3], [].concat(fn));
-
-  Function.prototype[Symbol.isConcatSpreadable] = true;
-  // Functions may be concat-spreadable
-  assertEquals([void 0, void 0, void 0], [].concat(function(a,b,c) {}));
-  Function.prototype[0] = 1;
-  Function.prototype[1] = 2;
-  Function.prototype[2] = 3;
-  assertEquals([1,2,3], [].concat(function(a, b, c) {}));
-
-  delete Function.prototype[Symbol.isConcatSpreadable];
-  delete Function.prototype[0];
-  delete Function.prototype[1];
-  delete Function.prototype[2];
-})();
-
-
-(function testConcatSpreadableRegExp() {
-  "use strict";
-  var re = /abc/;
-  // RegExps are not concat-spreadable by default
-  assertEquals([re], [].concat(re));
-
-  // RegExps may be individually concat-spreadable
-  re[Symbol.isConcatSpreadable] = true;
-  re[0] = 1, re[1] = 2, re[2] = 3, re.length = 3;
-  assertEquals([1, 2, 3], [].concat(re));
-
-  // RegExps may be concat-spreadable
-  RegExp.prototype[Symbol.isConcatSpreadable] = true;
-  RegExp.prototype.length = 3;
-
-  assertEquals([void 0, void 0, void 0], [].concat(/abc/));
-  RegExp.prototype[0] = 1;
-  RegExp.prototype[1] = 2;
-  RegExp.prototype[2] = 3;
-  assertEquals([1,2,3], [].concat(/abc/));
-
-  delete RegExp.prototype[Symbol.isConcatSpreadable];
-  delete RegExp.prototype[0];
-  delete RegExp.prototype[1];
-  delete RegExp.prototype[2];
-  delete RegExp.prototype.length;
-})();
-
-
-(function testArrayConcatSpreadableSparseObject() {
-  "use strict";
-  var obj = { length: 5 };
-  obj[Symbol.isConcatSpreadable] = true;
-  assertEquals([void 0, void 0, void 0, void 0, void 0], [].concat(obj));
-
-  obj.length = 4000;
-  assertEquals(new Array(4000), [].concat(obj));
-})();
-
-
-// ES5 tests
-(function testArrayConcatES5() {
-  "use strict";
-  var poses;
-  var pos;
-
-  poses = [140, 4000000000];
-  while (pos = poses.shift()) {
-    var a = new Array(pos);
-    var array_proto = [];
-    a.__proto__ = array_proto;
-    assertEquals(pos, a.length);
-    a.push('foo');
-    assertEquals(pos + 1, a.length);
-    var b = ['bar'];
-    var c = a.concat(b);
-    assertEquals(pos + 2, c.length);
-    assertEquals("undefined", typeof(c[pos - 1]));
-    assertEquals("foo", c[pos]);
-    assertEquals("bar", c[pos + 1]);
-
-    // Can we fool the system by putting a number in a string?
-    var onetwofour = "124";
-    a[onetwofour] = 'doo';
-    assertEquals(a[124], 'doo');
-    c = a.concat(b);
-    assertEquals(c[124], 'doo');
-
-    // If we put a number in the prototype, then the spec says it should be
-    // copied on concat.
-    array_proto["123"] = 'baz';
-    assertEquals(a[123], 'baz');
-
-    c = a.concat(b);
-    assertEquals(pos + 2, c.length);
-    assertEquals("baz", c[123]);
-    assertEquals("undefined", typeof(c[pos - 1]));
-    assertEquals("foo", c[pos]);
-    assertEquals("bar", c[pos + 1]);
-
-    // When we take the number off the prototype it disappears from a, but
-    // the concat put it in c itself.
-    array_proto["123"] = undefined;
-    assertEquals("undefined", typeof(a[123]));
-    assertEquals("baz", c[123]);
-
-    // If the element of prototype is shadowed, the element on the instance
-    // should be copied, but not the one on the prototype.
-    array_proto[123] = 'baz';
-    a[123] = 'xyz';
-    assertEquals('xyz', a[123]);
-    c = a.concat(b);
-    assertEquals('xyz', c[123]);
-
-    // Non-numeric properties on the prototype or the array shouldn't get
-    // copied.
-    array_proto.moe = 'joe';
-    a.ben = 'jerry';
-    assertEquals(a["moe"], 'joe');
-    assertEquals(a["ben"], 'jerry');
-    c = a.concat(b);
-    // ben was not copied
-    assertEquals("undefined", typeof(c.ben));
-
-    // When we take moe off the prototype it disappears from all arrays.
-    array_proto.moe = undefined;
-    assertEquals("undefined", typeof(c.moe));
-
-    // Negative indices don't get concated.
-    a[-1] = 'minus1';
-    assertEquals("minus1", a[-1]);
-    assertEquals("undefined", typeof(a[0xffffffff]));
-    c = a.concat(b);
-    assertEquals("undefined", typeof(c[-1]));
-    assertEquals("undefined", typeof(c[0xffffffff]));
-    assertEquals(c.length, a.length + 1);
-  }
-
-  poses = [140, 4000000000];
-  while (pos = poses.shift()) {
-    var a = new Array(pos);
-    assertEquals(pos, a.length);
-    a.push('foo');
-    assertEquals(pos + 1, a.length);
-    var b = ['bar'];
-    var c = a.concat(b);
-    assertEquals(pos + 2, c.length);
-    assertEquals("undefined", typeof(c[pos - 1]));
-    assertEquals("foo", c[pos]);
-    assertEquals("bar", c[pos + 1]);
-
-    // Can we fool the system by putting a number in a string?
-    var onetwofour = "124";
-    a[onetwofour] = 'doo';
-    assertEquals(a[124], 'doo');
-    c = a.concat(b);
-    assertEquals(c[124], 'doo');
-
-    // If we put a number in the prototype, then the spec says it should be
-    // copied on concat.
-    Array.prototype["123"] = 'baz';
-    assertEquals(a[123], 'baz');
-
-    c = a.concat(b);
-    assertEquals(pos + 2, c.length);
-    assertEquals("baz", c[123]);
-    assertEquals("undefined", typeof(c[pos - 1]));
-    assertEquals("foo", c[pos]);
-    assertEquals("bar", c[pos + 1]);
-
-    // When we take the number off the prototype it disappears from a, but
-    // the concat put it in c itself.
-    Array.prototype["123"] = undefined;
-    assertEquals("undefined", typeof(a[123]));
-    assertEquals("baz", c[123]);
-
-    // If the element of prototype is shadowed, the element on the instance
-    // should be copied, but not the one on the prototype.
-    Array.prototype[123] = 'baz';
-    a[123] = 'xyz';
-    assertEquals('xyz', a[123]);
-    c = a.concat(b);
-    assertEquals('xyz', c[123]);
-
-    // Non-numeric properties on the prototype or the array shouldn't get
-    // copied.
-    Array.prototype.moe = 'joe';
-    a.ben = 'jerry';
-    assertEquals(a["moe"], 'joe');
-    assertEquals(a["ben"], 'jerry');
-    c = a.concat(b);
-    // ben was not copied
-    assertEquals("undefined", typeof(c.ben));
-    // moe was not copied, but we can see it through the prototype
-    assertEquals("joe", c.moe);
-
-    // When we take moe off the prototype it disappears from all arrays.
-    Array.prototype.moe = undefined;
-    assertEquals("undefined", typeof(c.moe));
-
-    // Negative indices don't get concated.
-    a[-1] = 'minus1';
-    assertEquals("minus1", a[-1]);
-    assertEquals("undefined", typeof(a[0xffffffff]));
-    c = a.concat(b);
-    assertEquals("undefined", typeof(c[-1]));
-    assertEquals("undefined", typeof(c[0xffffffff]));
-    assertEquals(c.length, a.length + 1);
-
-  }
-
-  a = [];
-  c = a.concat('Hello');
-  assertEquals(1, c.length);
-  assertEquals("Hello", c[0]);
-  assertEquals("Hello", c.toString());
-
-  // Check that concat preserves holes.
-  var holey = [void 0,'a',,'c'].concat(['d',,'f',[0,,2],void 0])
-  assertEquals(9, holey.length);  // hole in embedded array is ignored
-  for (var i = 0; i < holey.length; i++) {
-    if (i == 2 || i == 5) {
-      assertFalse(i in holey);
-    } else {
-      assertTrue(i in holey);
-    }
-  }
-
-  // Polluted prototype from prior tests.
-  delete Array.prototype[123];
-
-  // Check that concat reads getters in the correct order.
-  var arr1 = [,2];
-  var arr2 = [1,3];
-  var r1 = [].concat(arr1, arr2);  // [,2,1,3]
-  assertEquals([,2,1,3], r1);
-
-  // Make first array change length of second array.
-  Object.defineProperty(arr1, 0, {get: function() {
-        arr2.push("X");
-        return undefined;
-      }, configurable: true})
-  var r2 = [].concat(arr1, arr2);  // [undefined,2,1,3,"X"]
-  assertEquals([undefined,2,1,3,"X"], r2);
-
-  // Make first array change length of second array massively.
-  arr2.length = 2;
-  Object.defineProperty(arr1, 0, {get: function() {
-        arr2[500000] = "X";
-        return undefined;
-      }, configurable: true})
-  var r3 = [].concat(arr1, arr2);  // [undefined,2,1,3,"X"]
-  var expected = [undefined,2,1,3];
-  expected[500000 + 2] = "X";
-
-  assertEquals(expected, r3);
-
-  var arr3 = [];
-  var trace = [];
-  var expectedTrace = []
-  function mkGetter(i) { return function() { trace.push(i); }; }
-  arr3.length = 10000;
-  for (var i = 0; i < 100; i++) {
-    Object.defineProperty(arr3, i * i, {get: mkGetter(i)});
-    expectedTrace[i] = i;
-    expectedTrace[100 + i] = i;
-  }
-  var r4 = [0].concat(arr3, arr3);
-  assertEquals(1 + arr3.length * 2, r4.length);
-  assertEquals(expectedTrace, trace);
-
-  // Clean up.
-  delete Array.prototype[123];
-  delete Array.prototype["123"];
-  delete Array.prototype["moe"];
-})();
-
-
-
-
-////////////////////////////////////////////////////////////////////////////////
-// Tests with proxies
-
-// Note: concat does not currently support species so there is no difference
-// between [].concat(foo) and Array.prototype.concat.apply(foo).
-
-
-var log = [];
-var logger = {};
-var handler = new Proxy({}, logger);
-
-logger.get = function(t, trap, r) {
-  return function(...args) {
-    log.push([trap, ...args]);
-    return Reflect[trap](...args);
-  }
-};
-
-
-(function testUnspreadableNonArrayLikeProxy() {
-  var target = {0: "a", 1: "b"};
-  var obj = new Proxy(target, handler);
-
-  log.length = 0;
-  assertEquals([obj], [].concat(obj));
-  assertEquals(1, log.length);
-  for (var i in log) assertSame(target, log[i][1]);
-  assertEquals(["get", target, Symbol.isConcatSpreadable, obj], log[0]);
-
-  log.length = 0;
-  assertEquals([obj], Array.prototype.concat.apply(obj));
-  assertEquals(1, log.length);
-  for (var i in log) assertSame(target, log[i][1]);
-  assertEquals(["get", target, Symbol.isConcatSpreadable, obj], log[0]);
-})();
-
-
-(function testSpreadableNonArrayLikeProxy() {
-  var target = {0: "a", 1: "b", [Symbol.isConcatSpreadable]: "truish"};
-  var obj = new Proxy(target, handler);
-
-  log.length = 0;
-  assertEquals([], [].concat(obj));
-  assertEquals(2, log.length);
-  for (var i in log) assertSame(target, log[i][1]);
-  assertEquals(["get", target, Symbol.isConcatSpreadable, obj], log[0]);
-  assertEquals(["get", target, "length", obj], log[1]);
-
-  log.length = 0;
-  assertEquals([], Array.prototype.concat.apply(obj));
-  assertEquals(2, log.length);
-  for (var i in log) assertSame(target, log[i][1]);
-  assertEquals(["get", target, Symbol.isConcatSpreadable, obj], log[0]);
-  assertEquals(["get", target, "length", obj], log[1]);
-
-  target.length = 3;
-
-  log.length = 0;
-  assertEquals(["a", "b", undefined], [].concat(obj));
-  assertEquals(7, log.length);
-  for (var i in log) assertSame(target, log[i][1]);
-  assertEquals(["get", target, Symbol.isConcatSpreadable, obj], log[0]);
-  assertEquals(["get", target, "length", obj], log[1]);
-  assertEquals(["has", target, "0"], log[2]);
-  assertEquals(["get", target, "0", obj], log[3]);
-  assertEquals(["has", target, "1"], log[4]);
-  assertEquals(["get", target, "1", obj], log[5]);
-  assertEquals(["has", target, "2"], log[6]);
-
-  log.length = 0;
-  assertEquals(["a", "b", undefined], Array.prototype.concat.apply(obj));
-  assertEquals(7, log.length);
-  for (var i in log) assertSame(target, log[i][1]);
-  assertEquals(["get", target, Symbol.isConcatSpreadable, obj], log[0]);
-  assertEquals(["get", target, "length", obj], log[1]);
-  assertEquals(["has", target, "0"], log[2]);
-  assertEquals(["get", target, "0", obj], log[3]);
-  assertEquals(["has", target, "1"], log[4]);
-  assertEquals(["get", target, "1", obj], log[5]);
-  assertEquals(["has", target, "2"], log[6]);
-})();
-
-
-(function testUnspreadableArrayLikeProxy() {
-  var target = ["a", "b"];
-  target[Symbol.isConcatSpreadable] = "";
-  var obj = new Proxy(target, handler);
-
-  log.length = 0;
-  assertEquals([obj], [].concat(obj));
-  assertEquals(1, log.length);
-  for (var i in log) assertSame(target, log[i][1]);
-  assertEquals(["get", target, Symbol.isConcatSpreadable, obj], log[0]);
-
-  log.length = 0;
-  assertEquals([obj], Array.prototype.concat.apply(obj));
-  assertEquals(1, log.length);
-  for (var i in log) assertSame(target, log[i][1]);
-  assertEquals(["get", target, Symbol.isConcatSpreadable, obj], log[0]);
-})();
-
-
-(function testSpreadableArrayLikeProxy() {
-  var target = ["a", "b"];
-  target[Symbol.isConcatSpreadable] = undefined;
-  var obj = new Proxy(target, handler);
-
-  log.length = 0;
-  assertEquals(["a", "b"], [].concat(obj));
-  assertEquals(6, log.length);
-  for (var i in log) assertSame(target, log[i][1]);
-  assertEquals(["get", target, Symbol.isConcatSpreadable, obj], log[0]);
-  assertEquals(["get", target, "length", obj], log[1]);
-  assertEquals(["has", target, "0"], log[2]);
-  assertEquals(["get", target, "0", obj], log[3]);
-  assertEquals(["has", target, "1"], log[4]);
-  assertEquals(["get", target, "1", obj], log[5]);
-
-  log.length = 0;
-  assertEquals(["a", "b"], Array.prototype.concat.apply(obj));
-  assertEquals(6, log.length);
-  for (var i in log) assertSame(target, log[i][1]);
-  assertEquals(["get", target, Symbol.isConcatSpreadable, obj], log[0]);
-  assertEquals(["get", target, "length", obj], log[1]);
-  assertEquals(["has", target, "0"], log[2]);
-  assertEquals(["get", target, "0", obj], log[3]);
-  assertEquals(["has", target, "1"], log[4]);
-  assertEquals(["get", target, "1", obj], log[5]);
-})();
-
-
-(function testSpreadableArrayLikeProxyWithNontrivialLength() {
-  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 obj = new Proxy(target, {get: getTrap, has: () => true});
-
-  assertEquals([undefined, undefined, "baz"], [].concat(obj));
-  assertEquals([undefined, undefined, "baz"], Array.prototype.concat.apply(obj))
-})();
-
-
-(function testSpreadableArrayLikeProxyWithBogusLength() {
-  var getTrap = function(t, key) {
-    if (key === "length") return Symbol();
-    if (key === "2") return "baz";
-    if (key === "3") return "bar";
-  };
-  var target = [];
-  var obj = new Proxy(target, {get: getTrap, has: () => true});
-
-  assertThrows(() => [].concat(obj), TypeError);
-  assertThrows(() => Array.prototype.concat.apply(obj), TypeError);
-})();