RFR: 8344372: Setting width for TRANSPARENT Stage -> gtk_window_resize: assertion 'height > 0' [v9]

[Thiago Milczarek Sayao]

> The bug happened when setting only width or height (not both) on a Stage that was oriented by the view size.
> 
> The fix just uses the previous value for width/height if not set.
> 
> The test class is designed to accept more test cases in the "mixed sizing" scenarios.

Thiago Milczarek Sayao has updated the pull request incrementally with one additional commit since the last revision:

  Address minor review observations

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1654/files
  - new: https://git.openjdk.org/jfx/pull/1654/files/6433d772..4902430e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1654&range=08
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1654&range=07-08

  Stats: 9 lines in 1 file changed: 4 ins; 1 del; 4 mod
  Patch: https://git.openjdk.org/jfx/pull/1654.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1654/head:pull/1654

PR: https://git.openjdk.org/jfx/pull/1654