Vulkan: Add WarmUpTaskCommon::mExecutableVk initialization Change is only for safety, because uninitialized member is not used in the current code. Bug: angleproject:8601 Change-Id: I65fa912119bc9c33a6248c5616388bde4d33b223 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5573393 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>