[LayoutNG] Create a new line breaker for each line.

Ok! Time to start landing this sequence of changes!

This creates a new NGLineBreaker for each line, and plumbs
information which was missing from the break token to properly
instantiate the line breaker again.

This change should have no change on test results.

There is a very hacky patch: https://chromium-review.googlesource.com/c/709716/4
Which has the final "working" (modulo a few bugs) version of how
this will all end up.

Bug: 635619
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng
Change-Id: If2f040bcbf69a27a1421abea1cec676605ac38f9
Reviewed-on: https://chromium-review.googlesource.com/703512
Commit-Queue: Koji Ishii <kojii@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#508607}
7 files changed