RFR: 8345261: Refactor the Dimension2D classes [v2]

[Nir Lisker]

> A small refactoring of the Dimension classes.
> 
> * `com.sun.javafx.geom.Dimension` was removed and its uses were replaced by `com.sun.javafx.geom.Dimension2D`.
> * `com.sun.javafx.geom.Dimension2D` became a record.
> * `javafx.geometry.Dimension2D`: fields became `final`.
> 
> I'm not sure we need the implementation class at all considering we are free to use the public one.

Nir Lisker has updated the pull request incrementally with one additional commit since the last revision:

  Address review comments

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/1653/files
  - new: https://git.openjdk.org/jfx/pull/1653/files/e1ce604a..2a72347f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1653&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1653&range=00-01

  Stats: 98 lines in 8 files changed: 53 ins; 37 del; 8 mod
  Patch: https://git.openjdk.org/jfx/pull/1653.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1653/head:pull/1653

PR: https://git.openjdk.org/jfx/pull/1653