<Swing Dev> RFR: 8231286: HTML font size too large with high-DPI scaling and W3C_LENGTH_UNITS

[Matthias Perktold]

This PR supersedes #2223.
The original PR was created from master, whereas this PR is created from a fresh branch.

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Commit messages:
 - Make fields volatile since changed from other thread, and put them on separate lines
 - Corrected copyright year
 - Space after comma in argument lists
 - Spaces around / operator
 - Fixed jcheck
 - Removed unnecessary imports
 - Convert tabs to spaces
 - Fix JDK-8231286

Changes: https://git.openjdk.java.net/jdk/pull/2256/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2256&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8231286
  Stats: 115 lines in 3 files changed: 101 ins; 6 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2256.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2256/head:pull/2256

PR: https://git.openjdk.java.net/jdk/pull/2256