RFR: 8353845: com.sun.javafx.css.BitSet.equals(null) throws NPE [v3]

[Michael Strauß]

> Fixes the bug that `BitSet.equals(null)` throws NPE.
> 
> A single reviewer should be sufficient.

Michael Strauß has updated the pull request incrementally with three additional commits since the last revision:

 - hashSet.equals(bitSet)
 - review comments
 - review comments

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/1766/files
  - new: https://git.openjdk.org/jfx/pull/1766/files/fda65a71..2da3bd93

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1766&range=02
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1766&range=01-02

  Stats: 19 lines in 3 files changed: 16 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jfx/pull/1766.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1766/head:pull/1766

PR: https://git.openjdk.org/jfx/pull/1766