Revert "Remove workaround for null klass during marking phase" am: 8b11184271 am: be568c0ff5

Original change: https://googleplex-android-review.googlesource.com/c/platform/art/+/18309591

Change-Id: I885670933843425a5b915c0cbb6bdec8d8526a9b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>