Unmark http/tests/htmlimports/import-script-nosniff.html

It is no longer crashing. Probably other crash fix like
r155738 fixes this as well.

BUG=267296
TBR=dominicc

Review URL: https://chromiumcodereview.appspot.com/22984004

git-svn-id: svn://svn.chromium.org/blink/trunk@155983 bbb929c8-8fbe-4397-9dbb-9b2b20218538