RFR: JDK-8266856 Make <wbr> element void

[Jonathan Gibbons]

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

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Commit messages:
 - Merge remote-tracking branch 'upstream/master' into wbr
 - JDK-8266856: Make <wbr> element void

Changes: https://git.openjdk.java.net/jdk/pull/4098/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4098&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8266856
  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 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