Mark css-parser/color3_hsl.html as Slow in Debug.

TBR=eseidel
BUG=330389

Review URL: https://codereview.chromium.org/120573002

git-svn-id: svn://svn.chromium.org/blink/trunk@164274 bbb929c8-8fbe-4397-9dbb-9b2b20218538