D3D9: Mark destination images dirty after CPU-copy path Fixes WebGL CTS failures for L and LA formats in: conformance/textures/image_bitmap_from_canvas conformance/textures/webgl_canvas Bug: angleproject:2192 Change-Id: If3a9bd81298c76320ed029617fd4965efe4e8ef0 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3076720 Commit-Queue: Alexey Knyazev <lexa.knyazev@gmail.com> Reviewed-by: Kenneth Russell <kbr@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>