Reland of [heap] Unify evacuating an object for new and old generation. (patchset #1 id:1 of https://codereview.chromium.org/1483963004/ )

Reason for revert:
Reland after fixing the potential root cause of the canary crasher.

Original issue's description:
> Revert of [heap] Unify evacuating an object for new and old generation. (patchset #2 id:20001 of https://codereview.chromium.org/1481873002/ )
>
> Reason for revert:
> Still investigating bad canary.
>
> Original issue's description:
> > [heap] Unify evacuating an object for new and old generation.
> >
> > BUG=chromium:524425
> > LOG=N
> >
> > Committed: https://crrev.com/afb8bcce8ba889280ed747eb218d287ddd233b4a
> > Cr-Commit-Position: refs/heads/master@{#32365}
>
> TBR=mlippautz@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=chromium:524425
>
> Committed: https://crrev.com/9c60ddc60e96da0c59e646660789c26550ad52a2
> Cr-Commit-Position: refs/heads/master@{#32460}

TBR=mlippautz@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:524425

Review URL: https://codereview.chromium.org/1494533002

Cr-Commit-Position: refs/heads/master@{#32501}