Vulkan: Fix mPipelineCache is not initialized after terminate Very old regression: https://chromium-review.googlesource.com/c/angle/angle/+/1683807 Problem happens only if call `eglInitialize()` again on terminated display without also calling `eglGetDisplay()`. Note: calling `eglGetDisplay()` on terminated display will call `setupDisplayPlatform()`, which will destroy old `mImplementation`. Test: angle_end2end_tests --gtest_filter=EGLDisplayTest.InitializeDrawSwapTerminateLoop* Bug: angleproject:3318 Change-Id: I94bc7eba97be2d9b194c1a22a37662a2836f60b4 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5717753 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>