RFR: 8277785: ListView scrollTo jumps to wrong location when CellHeight is changed [v4]

[Johan Vos]

> When the size of a ListCell is changed and a scrollTo method is invoked without having a layout calculation in between, the old (wrong) size is used to calculcate the total estimate. This happens e.g. when the size is changed in the `updateItem` method.
> This PR will immediately resize the cell and sets the new value in the cache containing the cellsizes.

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

  Don't shift cells if we are already showing the lowest index cell.

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/712/files
  - new: https://git.openjdk.java.net/jfx/pull/712/files/a931ba75..2b1b4bdc

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=712&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=712&range=02-03

  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/712.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/712/head:pull/712

PR: https://git.openjdk.java.net/jfx/pull/712