[CSSRegions] Move autoheight* tests into fast/regions/auto-size

Folder fast/regions/auto-size folder contains all the tests related to
css regions auto-height and auto-width computation as described in
http://dev.w3.org/csswg/css-regions/#regions-visual-formatting-details
This patch moves the remaining autoheight* tests, after autowidth* tests
were moved already. Modified paths inside the tests to account for movement.

BUG=306369

Review URL: https://codereview.chromium.org/27318002

git-svn-id: svn://svn.chromium.org/blink/trunk@160227 bbb929c8-8fbe-4397-9dbb-9b2b20218538