[LayoutNG] Move handling of new FCs into their own code-path.

HandleInflow was trying to do too much, we had a lot of !is_new_fc
checks to skip large portions of code.

In a followup patch new FCs will have a re-layout path and doesn't
nicely fall into a "layout then position" mode.

In another followup I'll remove the UpdateContentSize to just compute
the new content_size_ (and perhaps rename to auto_block_size_). We
currently don't use (and won't for a while) max_inline_size_.

This should not have any behaviour change.

Bug: 635619
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng
Change-Id: I1427fef8c4acbd0844bc1f2b91991294a372b91c
Reviewed-on: https://chromium-review.googlesource.com/680196
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Commit-Queue: Emil A Eklund <eae@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Cr-Commit-Position: refs/heads/master@{#503997}
2 files changed