RFR: JDK-8266856 Make <wbr> element void [v2]

[Jonathan Gibbons]

> Please review a simple fix to treat `wbr` as a void element.

Jonathan Gibbons has updated the pull request incrementally with one additional commit since the last revision:

  add test

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4098/files
  - new: https://git.openjdk.java.net/jdk/pull/4098/files/e933ce21..32c1c7ed

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4098&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4098&range=00-01

  Stats: 72 lines in 1 file changed: 72 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4098.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4098/head:pull/4098

PR: https://git.openjdk.java.net/jdk/pull/4098