When a platform key press or release event is repeated, we now pass
along a `repeat` flag to indicate that auto-repeating is happening. This
flag eventually ends up in `KeyboardEvent.repeat`.
The drag-and-drop processing model allows for users to drag around
either elements within the DOM or objects completely outside the DOM.
This drag event can either end without action (via cancellation or user
input), or in a drop event, where the dragged object is dropped onto
another element within the DOM.
The processing model is rather large. This implements enough of it to
allow the UI process to specifically handle dragging objects outside of
the DOM onto the DOM. For example, dragging an image from the OS file
manager onto a file-upload input element. This does not implement the
ability to drag DOM elements.
Now that all input events are handled by LibWebView, replace the IPCs
which send the fields of Web::KeyEvent / Web::MouseEvent individually
with one IPC per event type (key or mouse).
We can also replace the ad-hoc queued input structure with a smaller
struct that simply holds the tranferred Web::KeyEvent / Web::MouseEvent.
In the future, we can also adapt Web::EventHandler to use these structs.
The Serenity chrome is the only chrome thus far that sends all input key
and mouse events to WebContent, including shortcut activations. This is
necessary for all chromes - we must give web pages a chance to intercept
input events before handling them ourselves.
To make this easier for other chromes, this patch moves Serenity's input
event handling to LibWebView. To do so, we add the Web::InputEvent type,
which models the event data we need within LibWeb. Chromes will then be
responsible for converting between this type and their native events.
This class lives in LibWeb (rather than LibWebView) because the plan is
to use it wholesale throughout the Page's event handler and across IPC.
Right now, we still send the individual fields of the event over IPC,
but it will be an easy refactor to send the event itself. We just can't
do this until all chromes have been ported to this event queueing.
Also note that we now only handle key input events back in the chrome.
WebContent handles all mouse events that it possibly can. If it was not
able to handle a mouse event, there's nothing for the chrome to do (i.e.
there is no clicking, scrolling, etc. the chrome is able to do if the
WebContent couldn't).
