RFR: JDK-8305885: Use ReadOnly*PropertyBase class where possible [v3]

[John Hendrikx]

> These changes use base classes for custom properties where possible for the `ExpressionHelper` logic instead of duplicating these each time.

John Hendrikx has updated the pull request incrementally with one additional commit since the last revision:

  Rename properties to be more consistent

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1092/files
  - new: https://git.openjdk.org/jfx/pull/1092/files/eda5d621..c95635be

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1092&range=02
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1092&range=01-02

  Stats: 662 lines in 6 files changed: 320 ins; 320 del; 22 mod
  Patch: https://git.openjdk.org/jfx/pull/1092.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1092/head:pull/1092

PR: https://git.openjdk.org/jfx/pull/1092