code: function freezeArray(input) {
    var array = [];
    var l = input.length;
    for (var i = 0; i < l; i++) {
      if (i in input) {
        %object_define_property(array, i, {value: input[i],
                                           configurable: false,
                                           writable: false,
                                           enumerable: true});
      }
    }
  
    %object_define_property(array, 'length', {value: l, writable: false});
    return array;
  }
docs: Given an array-like, outputs an Array with the numbered
  properties copied over and defined
  configurable: false, writable: false, enumerable: true.