Update D8 and R8 to 8.3.19-dev am: 9bf0129317 am: 49105c9368

Original change: https://android-review.googlesource.com/c/platform/prebuilts/r8/+/2843640

Change-Id: I21fd9804ef0d1856d20b0e9e0281e9dafc47d64a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>