Revert "[css-anchor-position-1] Fix flicker with try-option with fixe…

…d-position anchor"

This reverts commit 94af1f503694c3a7ffece9c910516b3bbe9d50c2.

Reason for revert: Causing crashes in GC, see bug.

Bug: 339967265, 338929745

Original change's description:
> [css-anchor-position-1] Fix flicker with try-option with fixed-position anchor
>
> Previously we supposed the default anchor wouldn't change in
> try-options, but the latest draft spec allows that.
>
> When the currently tried option will use a default anchor that is
> different from the currently used default anchor, checking overflow
> with the snapshotted AnchorPositionScrollData will be incorrect,
> and the incorrect results caused oscillation between try options.
>
> To resolve that, when the total offset is requested for a different
> default anchor, we need to calculate it on the fly instead of getting
> it from the snapshotted result.
>
> Also allow one more layout if ValidateSnapshot() (called after the
> first layout in a document lifecycle update) finds that the
> snapshotted scroll data needs update, to ensure correct layout and
> paint with the changed anchor and scroll adjustment in most cases.
>
> In rare cases when we need more than one additional layout to get
> the stable layout, ShouldScheduleNextService() will schedule another
> lifecycle.
>
> Fixed: 338929745
> Change-Id: I295fbc605ac8b7f0298eef7aeff4434c6bd54628
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5529048
> Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
> Reviewed-by: Philip Rogers <pdr@chromium.org>
> Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1299608}

Change-Id: I222274aa6af5da55d5d6dc0867d3cda684efff49
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5526668
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1299965}