Revert of Add support of leader_point in NGLayoutOpportunityIterator. (patchset #3 id:40001 of https://codereview.chromium.org/2472583006/ )

Reason for revert:
Causing a failure on Mac MSAN:

https://build.chromium.org/p/chromium.memory/builders/Mac%20ASan%2064%20Tests%20%281%29/builds/23812

Original issue's description:
> Add support of leader_point in NGLayoutOpportunityIterator.
>
> Leader point together with origin_point creates a temporary exclusion that should be avoided in the layout opportunity iterator.
>
> BUG=635619
>
> Committed: https://crrev.com/2e09ff76918cbd153161b9ab1062e690eb67d3ab
> Cr-Commit-Position: refs/heads/master@{#429650}

TBR=ikilpatrick@chromium.org,atotic@chromium.org,cbiesinger@chromium.org,glebl@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=635619

Review-Url: https://codereview.chromium.org/2477843002
Cr-Commit-Position: refs/heads/master@{#429672}
5 files changed