Metal: Fix 2D array texture's robust resource init 2D array texture's robust resource init didn't work due to mtl::InitializeTextureContents() expects one slice at a time, however TextureMtl::initializeContents() created entire layers index via GetZeroLevelIndex() before passing to mtl::InitializeTextureContents(). Fixed by changing to GetLayerMipIndex() instead. Bug: angleproject:2634 Change-Id: Ie8d80d927a987c2b393d913fda8288b6e06e97d0 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2494527 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Le Hoang Quyen <le.hoang.q@gmail.com>