Revert "Add some layout tests to explicitly test dynamic translateZ changes."

Revert "Mark virtual/softwarecompositing/layer-creation/translatez-removed.html as failing"

This reverts r171191 as the newly added test fails on all platforms.

http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20Blink&tests=compositing%2Flayer-creation%2Ftranslatez-removed.html

BUG=361987,361729
TBR=danakj@chromium.org,enne@chromium.org

Review URL: https://codereview.chromium.org/232863002

git-svn-id: svn://svn.chromium.org/blink/trunk@171255 bbb929c8-8fbe-4397-9dbb-9b2b20218538