Update D8 and R8 to 8.3.21-dev am: f41676e361 am: 5ecb0f119c am: 35259085b3

Original change: https://android-review.googlesource.com/c/platform/prebuilts/r8/+/2856147

Change-Id: I4d41338adb9f656f7c251f1e1a3d61f929c65653
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>