Don't delete a flow thread just because it becomes childless.
This is a revert of overzealous cleanup done in
https://codereview.chromium.org/769093002
Let's update the comment instead. A flow thread needs to exist as long
as its parent multicol/paged container exists. A flowthread's lifespan
does not depend on its children.
R=jchaffraix@chromium.org
BUG=438573
Review URL: https://codereview.chromium.org/776653003
git-svn-id: svn://svn.chromium.org/blink/trunk@186484 bbb929c8-8fbe-4397-9dbb-9b2b20218538
3 files changed
