Don't wait for current submission inside of submit (#2824)

Author: cwfitzgerald

wgpu-core/src/device/queue.rs

@@ -1074,7 +1074,7 @@ impl<G: GlobalIdentityHandlerFactory> Global<G> {
 
             // This will schedule destruction of all resources that are no longer needed
             // by the user but used in the command stream, among other things.
-            let (closures, _) = match device.maintain(hub, wgt::Maintain::Wait, &mut token) {
+            let (closures, _) = match device.maintain(hub, wgt::Maintain::Poll, &mut token) {
                 Ok(closures) => closures,
                 Err(WaitIdleError::Device(err)) => return Err(QueueSubmitError::Queue(err)),
                 Err(WaitIdleError::StuckGpu) => return Err(QueueSubmitError::StuckGpu),