[8u] Review request: 8190249: Missing content from cssref.html due to missed closing comment

[Kevin Rushforth]

Phil,

Please review this simple fix for a regression introduced by a bad patch 
when backporting a fix to 8u-dev:

https://bugs.openjdk.java.net/browse/JDK-8190249

The diff is in the bug report (it just adds a missing closing comment 
and a blank line).

-- Kevin