text: // IM has the following fastpaths:
  // - constant index (constant)
  // - need negative int check (neg)
  // - needs hole check (hole)
  // So to test everything we have to do:
  //            constant | neg | hole
  //  test 1:     0         0      0
  //  test 2:     1         0      0
  //  test 3:     0         1      0
  //  test 4:     1         1      0
  //  test 5:     0         0      1
  //  test 6:     1         0      1
  //  test 7:     0         1      1
  //  test 8:     1         1      1
  
  function test1(index, a) {
    if (index < 0)
      index = -index
    return index in a;
  }
  assertEq(test1(1, [1,2]), true);
  
  function test2(a) {
    return 0 in a;
  }
  assertEq(test2([1,2]), true);
  
  function test3(index, a) {
    return index in a;
  }
  
  var arr3 = [];
  arr3["-1073741828"] = 17;
  assertEq(test3(-1073741828, arr3), true);
  
  function test4(a) {
    return -1073741828 in a;
  }
  assertEq(test4(arr3), true);
  
  
  function test5(index, a) {
    if (index < 0)
      index = -index
    return index in a;
  }
  var arr5 = [];
  arr5[0] = 1
  arr5[1] = 1
  arr5[2] = 1
  arr5[4] = 1
  assertEq(test5(1, arr5), true);
  assertEq(test5(3, arr5), false);
  
  function test7a(a) {
    return 3 in a;
  }
  function test7b(a) {
    return 4 in a;
  }
  assertEq(test7a(arr5), false);
  assertEq(test7b(arr5), true);
  
  function test8(index, a) {
    return index in a;
  }
  arr5["-1073741828"] = 17;
  assertEq(test8(-1073741828, arr5), true);
  assertEq(test8(3, arr5), false);
  assertEq(test8(0, arr5), true);
  
  function test9a(a) {
    return 0 in a;
  }
  function test9b(a) {
    return 3 in a;
  }
  function test9c(a) {
    return -1073741828 in a;
  }
  assertEq(test9a(arr5), true);
  assertEq(test9b(arr5), false);
  assertEq(test9c(arr5), true);
  