This will allow us to remove the use of SafeFunction in it's
implementation. This requires a fair amount of plumbing to wire up the
GC heap to the appropriate places in order to create the timers.
Instead of using Core::EventLoop and Core::Timer directly, LibWeb now
goes through a Web::Platform abstraction layer instead.
This will allow us to plug in Qt's event loop (and QTimer) over in
Ladybird, to avoid having to deal with multiple event loops.
