Despite being a 'client resource', the window can become invalid due to
events outside of the client code's control, which causes
XGetWindowAttributes to fail because it retrieves servers-side data
that is no longer available. Hence it is something we should expect to
see happen, and not (always) an indication of a bug that needs fixing.
Also, we should be able to safely continue with an invalid window.

At this point it's up to the client code to catch the X error and
handle it appropriately. The EGL spec does not indicate that it should
catch it instead and generate an error (eglSwapBuffers can generate
EGL_CONTEXT_LOST but that's reserved for power management events).

Bug chromium:861882
Bug chromium:824522

Change-Id: I78a364516b9466f652c94de68553369935590bde
Reviewed-on: https://swiftshader-review.googlesource.com/19868Reviewed-by: Antoine Labour <piman@chromium.org>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>