Handling crashes synchronously is finicky since we're modifying the
m_client_state struct while in a callback lambda owned by it.
Let's avoid all the footguns here by simply using deferred_invoke()
and handling the crash on next event loop iteration instead.
This patch adds an IPC call for debugging requests. It's stringly typed
and very simple, and allows us to easily implement all the features in
the Browser's Debug menu.
The OOPWV will now detect WebContent process crashes/disconnections and
simply create a new WebContent process in its place. We also generate a
little error page with a link to the crashing URL so you can reload and
try again.
This a huge step forward for OOPWV since it now has a feature that IPWV
can never replicate. :^)
To support this, the GUI process and the WebContent service will now
coordinate their backing store bitmaps. Each backing store can be
referred to by a serial ID, and we don't need to keep resending it
as a file descriptor.
We should probably do something similar in WindowServer. :^)
