Make copyDepthStencil more robust to texture format table changes This will make it easier to verify changes to integer texture DXGI formats. Currently the DXGI format info table contains some values that wouldn't make sense after the integer formats are changed, such as R32_TYPELESS being recorded as a depth format, and we need to make sure no code relies on this kind of information to make changing the table safe. Includes cleaning up unused depth/stencil offset fields from DXGIFormatInfo. BUG=angleproject:1244 TEST=dEQP-GLES3.functional.fbo.blit.*depth* Change-Id: I0149f28e4c6f961af99ac2f5a656f3fbfe13aee6 Reviewed-on: https://chromium-review.googlesource.com/328964 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>