This change makes  RepToPointer/PointerToRep have 0 instructions.
This makes IsMovedFrom simpler (although this could always have left out the IsInlined check since that bit can never be set on the aligned pointer)

In exchange, it makes CodeToInlinedRep slower, but does not inhibit replacing it with a constant.
InlinedRepToCode is unaffected.

PiperOrigin-RevId: 562826801
Change-Id: I2732f04ab293b773edc2efdec546b3a287b980c2