An object that encapsulates text changed events for textareas
and input element of type text and password. This event only occurs when the
element is focused (which means that using drag and drop will not trigger
the event because the element does not have focus at that time).
Note: this does not guarantee the correctness of {@code keyCode} or
{@code charCode}, or attempt to unify them across browsers. See
{@code goog.events.KeyHandler} for that functionality.
Known Issues: It does not trigger for drop events
Known Issues: WebKit does not fire input event in textareas.