RFR: 8298728: Cells in VirtualFlow jump after resizing [v3]

[Johan Vos]

> When recalculating sizes, we often don't want the current index and/or offset to change.
> 
> Allow to fix the index/offset when doing recalculations.
> 
> Fix JDK-8298728

Johan Vos has updated the pull request incrementally with one additional commit since the last revision:

  Process reviewer comments: fix typos (add space)

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Changes:
  - all: https://git.openjdk.org/jfx/pull/974/files
  - new: https://git.openjdk.org/jfx/pull/974/files/5d4474fb..4ce32b70

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=974&range=02
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=974&range=01-02

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jfx/pull/974.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/974/head:pull/974

PR: https://git.openjdk.org/jfx/pull/974