function createTransferStrategy(mergeStrategy) {
  return function(props, key, value) {
    if (!props.hasOwnProperty(key)) {
      props[key] = value;
    } else {
      props[key] = mergeStrategy(props[key], value);
    }
  };
}
Transfer props from this component to a target component.

Props that do not have an explicit transfer strategy will be transferred
only if the target component does not already have the prop set.

This is usually used to pass down props to a returned root component.

@param {ReactElement} element Component receiving the properties.
@return {ReactElement} The supplied `component`.
@final
@protected