Mark compositing/repaint/transform-style-change.html as flaky after rebaseline

BUG=265650
TBR=ojan

Review URL: https://codereview.chromium.org/21165003

git-svn-id: svn://svn.chromium.org/blink/trunk@155105 bbb929c8-8fbe-4397-9dbb-9b2b20218538