Don't include trailing comment characters in javascript snippets.

This trailing "/*" (and so forth) do not contribute very much to the signal, and not using them allows us to
catch some interesting corner cases involving server-side page post-processors.

BUG=355479

Review URL: https://codereview.chromium.org/210033008

git-svn-id: svn://svn.chromium.org/blink/trunk@169967 bbb929c8-8fbe-4397-9dbb-9b2b20218538