both work because of the way the magic call is implemented in WebElement, but ``postValue`` is the canonical name for this action: https://github.com/instaclick/php-webdriver/commit/2a5d9f443f082e6e2de4cb375b7429f512fa48a3
This is why Scrutinizer is complaining about the undefined method btw (I fixed 1 occurrence here, and the other occurrence is fixed in #147)