Dawn backend: update to accommodate recent Skia changes.

"Lift calls for setting dynamic state to Ganesh level" (https://skia-review.googlesource.com/c/skia/+/271976)
"Update nanobench and skpbench to use flush API for gpu syncing" (https://skia-review.googlesource.com/c/skia/+/272456)

Change-Id: I3026a5d6649ecd45b421c89e80cf065ce22f156e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/273336
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Chris Dalton <csmartdalton@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
5 files changed