Correct overflow propagation in BTT and RTL writing-modes

Overflow rectangles are not quite physical, not quite logical. This
means that we cannot use clientBoxRect() directly to represent a
rectangle that expresses exactly no overflow. This rectangle is the
padding box (relative to the border box) in vertical-lr and
horizontal-tb, but the block-direction borders need to be flipped in
vertical-rl and horizontal-bt.

fast/multicol/vertical-rl/rules-with-border-before.html now needs a
rebaseline, because it now renders differently, but correctly.

R=
BUG=236326

Review URL: https://chromiumcodereview.appspot.com/18720003

git-svn-id: svn://svn.chromium.org/blink/trunk@154945 bbb929c8-8fbe-4397-9dbb-9b2b20218538