Avoid VarHandle checks for boot image field VarHandles. am: 9d31daa0b3 am: f08f2e3895 am: c9cddc2284

Original change: https://android-review.googlesource.com/c/platform/art/+/2069110

Change-Id: I954f04f183df413ba9363f3b05c12fa2cf6d73a3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>