Vulkan: Fix invalid assert in ContextVk::onSurfaceUnMakeCurrent Old assert checked "mHasWaitSemaphoresPendingSubmission". However this will be true even after "mWaitSemaphores" are flushed to the Renderer. Correct assert is to check that everything is flushed, but may be pending submission. Bug: angleproject:8017 Change-Id: I831ece236fb0cecb8520315ebaa5207f90d3dfc6 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4270931 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>