Revert of [compiler] Make feedback vector cope with flag changes. (patchset #1 id:1 of https://codereview.chromium.org/1869693003/ )

Reason for revert:
Blocks current roll: https://codereview.chromium.org/1876713002/ according to bisect: https://codereview.chromium.org/1872353002/#ps80001

Original issue's description:
> [compiler] Make feedback vector cope with flag changes.
>
> This fixes corner cases where the layout of feedback vectors baked into
> the snapshot is different from the expected layout, depending on some
> runtime flags. We make sure the feedback vector is regenereated for
> functions that are not compiled. Flag changes of this kind are only
> allowed when code is not serialized.
>
> An alternative solution would be to not serialize the feedback vector
> for such cases in the first place. That solution however would have a
> higher overhead, as it would required the serializer to be able to
> recognize feedback vectors while generating a snapshot.
>
> R=mvstanton@chromium.org
> TEST=mjsunit/regress/regress-crbug-600995
> BUG=chromium:600995
> LOG=n
>
> Committed: https://crrev.com/460bff5fb6af2bd79e610f89afdf6da9dba3cf0c
> Cr-Commit-Position: refs/heads/master@{#35339}

TBR=mvstanton@chromium.org,mstarzinger@chromium.org

BUG=chromium:600995
LOG=N
NOTRY=true

Review URL: https://codereview.chromium.org/1876103002

Cr-Commit-Position: refs/heads/master@{#35392}