This patch moves the wrapper code from the remembered-set to the
scavenger and the mark-compact code.

The wrapper code inspected a slot address to see if the object that
belongs to the address is in the from-space. If it was in the
from-space, then some callback was executed on the object. If the object
got move to the to-space, then the wrapper returned KEEP_SLOT, otherwise
REMOVE_SLOT.

This logic does not really belong to the remembered set, so I moved it
away from there.

R=ulan@chromium.org

Review-Url: https://codereview.chromium.org/1994933002
Cr-Commit-Position: refs/heads/master@{#36364}