It's mandatory to reply to a xdg_surface.configure with a
xdg_surface.ack_configure, as well as a wl_surface.commit to have the
ack_configure to have any effect. We failed to do that if the new
configuration didn't cause any actual anything to change, meaning we'd
just ack_configure, but potentially never commit.
Fix this by requesting a 'after-paint' frame clock phase, while setting
the pending commit state to true. If we were already to paint, the new
requested phase would happen anyway, but to avoid double
wl_surface.commit when also using eglSwapBuffers*(), also avoid
performing the commit if we know the swap buffers will happen.
bdddc3857c