Rewrote multicol/newmulticol/column-rules-fixed-height and moved it to fast/multicol/

It's a pure reftest now. It used to compare between the old and new
implementations, until settings.setRegionBasedColumnsEnabled(true)
got removed from a lot of tests a couple of months ago, at which point
the test and the ref essentially became identical.

R=jchaffraix@chromium.org

Review URL: https://codereview.chromium.org/508953004

git-svn-id: svn://svn.chromium.org/blink/trunk@181248 bbb929c8-8fbe-4397-9dbb-9b2b20218538