To account for framebuffer flipping, `dFdy()` expressions must be changed to: dFdy() * ANGLEUniforms.viewportYScale Bug: angleproject:3487 Test: dEQP-GLES3.functional.shaders.derivate.dfdy.* Change-Id: I38f25ba37fb8c5ae61cee5ac911df88ec4a93fef Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1678404 Commit-Queue: Tim Van Patten <timvp@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
