[CSS Regions] Minor fixes in regions performance tests

[CSS Regions] Minor fixes in regions performance tests
https://bugs.webkit.org/show_bug.cgi?id=127041

Reviewed by Ryosuke Niwa.

Fix minor issues in CSS Regions performance tests.

* Layout/RegionsAuto.html: Change type to lower case.
* Layout/RegionsAutoMaxHeight.html: Ditto.
* Layout/RegionsFixed.html: Ditto.
* Layout/RegionsFixedShort.html: Ditto.
* Layout/RegionsSelection.html: Ditto. Move test methods from regions.js.
* Layout/resources/regions.js: Remove moved methods.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@162223 268f45cc-cd09-0410-ab3c-d52691b4dbfc