WebGPU: Ensure mDefaultBindGroup is created mDefaultBindGroup would not be created if the program has no uniforms because they are not dirty. Mark all stages as dirty after linking. Bug: angleproject:376553328 Change-Id: I1663791fa1642be052948c5acb8e403fa8b844f9 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6039006 Reviewed-by: Matthew Denton <mpdenton@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>