Revert "x86/x86-64: Avoid temporary for read barrier field load."

Fault handler does not recognize the instruction
    F6 /0 ib    TEST r/m8, imm8
so we get crashes instead of NPEs.

Bug: 29966877
Bug: 12687968

This reverts commit ccf06d8f19a37432de4a3b768747090adfbd18ec.

Change-Id: Ib7db3b59f44c0d3ed5e24a20b6c6ee596a89d709
15 files changed