Enable TexSubImage workaround on D3D11. This workaround uses UpdateResource instead of staging buffers for texture data updates. It improves performance for highly dynamic textures, especially in some benchmarks, eg the turbulenz particle demo. BUG=angle:729 BUG=365078 Change-Id: Idd82c27845a772199caef3695111c96735e8843e Reviewed-on: https://chromium-review.googlesource.com/219864 Tested-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>