D3D11: Use TextureHelper11 everywhere. This consolidates all texture allocation into ResourceManager11. It removes a lot of error checking and resource management code. In a few places we're storing some redundant information, like in TextureStorage11, we might store the Format pointer in two places, or the Texture's size. BUG=angleproject:2034 Change-Id: I9369e76925a67632c444c662e5667c5ed7875547 Reviewed-on: https://chromium-review.googlesource.com/503252 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>