When a mousewheel scroll event isn't handled by the web content
itself (e.g. an overflowed box or similar), the event needs to get
passed back up to the OutOfProcessWebView.
We'll want to remove the LibGUI dependency from the WebContent process.
This is the first basic step of removing unnecessary LibGUI includes
and swapping out GUI::Painter for Gfx::Painter.
This is a workaround until we can implement a proper <input type=text>
in terms of LibWeb primitives.
This makes google.com not crash in multi-process mode (but there is no
search box.)
