RFR: 8289587: IllegalArgumentException: Color.rgb's red parameter (-16776961) expects color values 0-255 [v3]

[Jose Pereda]

> This PR solves an IAE exception that happens when invoking a ColorChooser control within a WebView, by getting the r, g, b values from the Color before calling the colorChooser.
> 
> A system test is included, to verify that there is no exception and the two native functions that are modified produce the expected color components.

Jose Pereda has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Merge branch 'master' into 8289587-colorrgb
 - Rework test
 - Get rgb values from color before calling colorChooser, including test

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Changes:
  - all: https://git.openjdk.org/jfx/pull/809/files
  - new: https://git.openjdk.org/jfx/pull/809/files/c94e695e..31348ab3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=809&range=02
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=809&range=01-02

  Stats: 19 lines in 4 files changed: 3 ins; 11 del; 5 mod
  Patch: https://git.openjdk.org/jfx/pull/809.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/809/head:pull/809

PR: https://git.openjdk.org/jfx/pull/809