Avoid VarHandle checks for boot image field VarHandles. am: 9d31daa0b3 am: f08f2e3895 am: c9cddc2284 am: 3632dfe682

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

Change-Id: I156f491da74de7e95e6282d4807d4a4bd4d7179b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>