[LayoutNG] Don't run the OOFLayoutPart if we have any adjoining floats.

If we have adjoining floats we'll revisit the node to correctly place
floats. During the first pass we may not have floats present within
lineboxes, causing NGContainerFragmentBuilder::GetChildOffset to fail.

This makes sure we don't run the OOFLayoutPart for this condition.

There is a followup cleanup patch I'll send out for review later which
speculatively places floats avoiding this condition also:
https://chromium-review.googlesource.com/c/chromium/src/+/1619047

Bug: 976397
Change-Id: I10db8207357572521fc9103134cb6fbf885c4a94
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1676727
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672423}