[jfx-tests] RFR: 8316097: Some Scenegraph/richtext tests fail due to IllegalStateException [v2]

[Ajit Ghaisas]

> test/scenegraph/richtext/RichTextLabeledsTest.java
> test/scenegraph/richtext/RichTextMixedTest.java
> test/scenegraph/richtext/RichTextRectangleTest.java
> test/scenegraph/richtext/RichTextTextTest.java
> 
> These tests were failing with -  java.lang.IllegalStateException: This operation is permitted on the event thread only; currentThread = Time-limited test. They are fixed with a change to single file `RichTextPropertiesApp.java`
> 
> Another test - test/scenegraph/richtext/RichTextSpecSymbTest.java - was failing due to NPE. Added a null check to fix it.

Ajit Ghaisas has updated the pull request incrementally with one additional commit since the last revision:

  review comment fix

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

Changes:
  - all: https://git.openjdk.org/jfx-tests/pull/9/files
  - new: https://git.openjdk.org/jfx-tests/pull/9/files/08672c8c..ae6b1fc7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx-tests&pr=9&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx-tests&pr=9&range=00-01

  Stats: 8 lines in 1 file changed: 0 ins; 6 del; 2 mod
  Patch: https://git.openjdk.org/jfx-tests/pull/9.diff
  Fetch: git fetch https://git.openjdk.org/jfx-tests.git pull/9/head:pull/9

PR: https://git.openjdk.org/jfx-tests/pull/9