RFR: JDK-8275273: Add missing HtmlStyle documentation [v2]

[Hannes Wallnöfer]

> Please review this simple change to add doc comments to the so far undocumented `HtmlStyle` constants. I also removed one more unused constant (memberNameLabel).

Hannes Wallnöfer has updated the pull request incrementally with one additional commit since the last revision:

  Address PR comments

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5944/files
  - new: https://git.openjdk.java.net/jdk/pull/5944/files/a39250d1..4008328c

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5944&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5944&range=00-01

  Stats: 16 lines in 1 file changed: 6 ins; 8 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5944.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5944/head:pull/5944

PR: https://git.openjdk.java.net/jdk/pull/5944