<Swing Dev> RFR: 8258924: javax/swing/JSplitPane/4201995/bug4201995.java fails in GTk L&F [v2]

[Prasanta Sadhukhan]

> This test tests whether SplitPane is opaque or not but in nimbus and subseqeuently in GTK L&F the opaque property is set to false [1]
> As nimbus is already handled in the test, it is modified to handle GTK L&F too. Along with this modification, the test is also updated to test all installed L&Fs.
> Mach5 job running for several iterations for all platform is ok. Link in JBS.
> 
> [1] https://raw.githubusercontent.com/openjdk/jdk/master/src/java.desktop/share/classes/javax/swing/plaf/nimbus/skin.laf
>       uiComponent opaque="false" type="javax.swing.JSplitPane" name="SplitPane" ui="SplitPaneUI" subregion="false"

Prasanta Sadhukhan has updated the pull request incrementally with one additional commit since the last revision:

  Continue to next L&F if current one is unsupported

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1888/files
  - new: https://git.openjdk.java.net/jdk/pull/1888/files/e13fb594..c357bd8f

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1888&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1888&range=00-01

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1888.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1888/head:pull/1888

PR: https://git.openjdk.java.net/jdk/pull/1888