Vulkan: Fix cleanup race condition on Context destroy In Context::onDestroy(), e7b3fe21866454bd3ea983acede162d34ae03dd8 had moved surface deletion first which down the line caused RendererVk::finish() to be called. bf7b95db6b6f039f6c8797f1f4b930d46a761828 however made surface deletion unnecessary, which means finish was never called. This commit adds an explicit finish in Context::onDestroy(). In truth, the wait is only necessary until all command buffers submitted for this particular context have finished. This optimization is deferred to a possible future work. Bug: angleproject:2811 Change-Id: I56e6c88d3b4a6ec73f70d80d7775a0c85be651ea Reviewed-on: https://chromium-review.googlesource.com/c/1302838 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>