Fix a resource leak in insecure-websocket-in-secure-page-worker.html

This is a speculative fix for a leak reported by a leak bot.

BUG=672740

Review-Url: https://codereview.chromium.org/2587943002
Cr-Commit-Position: refs/heads/master@{#439696}
1 file changed