Code Cleanup In validationES.cpp, the framebuffer is required to have 0 depth bits (to conform to OpenGL ES 3.2 specifications). That is, ImageHelper::copyImageDataToBuffer() will not be called on a buffer with combined depth and stencil format. Replacing the lines relating to testing combined depth and stencil format ImageHelper::copyImageDataToBuffer() with an assert. Bug: angleproject:6856 Change-Id: I911500910b2065eb21c72d7f2d8ff481f4afa304 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3680862 Reviewed-by: Charlie Lao <cclao@google.com> Reviewed-by: Amirali Abdolrashidi <abdolrashidi@google.com> Commit-Queue: Faye Zhang <ffz@google.com>