Remove unverifiable assertions from VisitRefsForCompaction am: b73e8ce972

Original change: https://android-review.googlesource.com/c/platform/art/+/2980792

Change-Id: I611cca307af960688cec2b1c48ec2ca4c891c066
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>