[LayoutNG] Rebaseline width-avoid-floats.html

This adds a new test expectation file for the width-avoid-floats.html
test.

We believe that if/when fill-available does get specified, it should
avoid floats similar to 'auto'.

Bug: 635619
Change-Id: I1c112952ea70176c55106d9bd396034cbf5ca531
Reviewed-on: https://chromium-review.googlesource.com/c/1393667
Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619638}
2 files changed