Create FloatingObject from NG Fragment in old Layout tree

This will create FloatingObjects from fragments in old Layout tree. FloatingObjects are required by BlockFlowPainter that uses them to paint floats.
BUG=635619

Review-Url: https://codereview.chromium.org/2423263002
Cr-Commit-Position: refs/heads/master@{#425896}
1 file changed