Revert "Use the holder's gray bit in Baker read barrier slow paths (ARM, ARM64)."

This reverts commit 27b1f9cbfc1409418eee4b0e22f29f033e10b64d.

This change (along with https://android-review.googlesource.com/#/c/342428/)
creates null pointer dereferences.

Bug: 35780827
Bug: 29516974
Change-Id: If731960a405f9b89528f3daaf235da57cabc5c11
3 files changed