Merge 3809: [LayoutNG] Fix float + nbsp to create a break opportunity

Floats should create break opportunities, and
|NGLineBreaker::Rewind()| assumes this. However, |nbsp|
after floats suppressed the break opportunity, which caused
NGLineBreaker to loop infinitely under certain conditions.

This patch fixes floats to allow break after them.

Note the new behavior is the same as Gecko.

(cherry picked from commit 7b1e6a920eb103abedf45c95f5d86dda52d8713c)

Bug: 972421
Change-Id: Ie8c1d7927c5c282078a20f90941398149ea702a3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1653171
Commit-Queue: Koji Ishii <kojii@chromium.org>
Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#668681}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1660076
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/branch-heads/3809@{#362}
Cr-Branched-From: d82dec1a818f378c464ba307ddd9c92133eac355-refs/heads/master@{#665002}

• third_party/blink/renderer/core/layout/ng/inline/ng_line_breaker.cc[diff]
• third_party/blink/web_tests/external/wpt/css/css-text/word-break/word-break-break-word-crash-001.html[Added - diff]