RFR: 8029451 : Tidy warnings cleanup for java.util package

[Sergey Lugovoy]

Hi all,
please review the fix
http://cr.openjdk.java.net/~yan/8029451/webrev.01/
for
https://bugs.openjdk.java.net/browse/JDK-8029451

This patch cleanup tidy warnings for generated html documentation, and do
not affect the appearance of the documentation.

Best regards,
Serge V. Lugovoy