function baseAssignValue(object, key, value) {
  if (key == '__proto__' && defineProperty) {
    defineProperty(object, key, {
      'configurable': true,
      'enumerable': true,
      'value': value,
      'writable': true
    });
  } else {
    object[key] = value;
  }
}
The base implementation of `assignValue` and `assignMergeValue` without
value checks.

@private
@param {Object} object The object to modify.
@param {string} key The key of the property to assign.
@param {*} value The value to assign.