fast/html/imports/import-style-link.html is flaky on all platforms.

It appears that script isn't consistently being blocked inside the imported file as the test expects.

http://test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=fast%2Fhtml%2Fimports%2Fimport-style-link.html has details.

BUG=326153
TBR=dglazkov@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/105843006

git-svn-id: svn://svn.chromium.org/blink/trunk@163262 bbb929c8-8fbe-4397-9dbb-9b2b20218538