RFR: 8347359: RichTextArea API Tests

[Andy Goryachev]

Additional RichTextArea API tests.

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

Commit messages:
 - Merge remote-tracking branch 'origin/master' into 8347359.rta.api.tests
 - Merge remote-tracking branch 'origin/8348736.rta.followup.2' into 8347359.rta.api.tests
 - review comments
 - Merge remote-tracking branch 'origin/8348736.rta.followup.2' into
 - newlines
 - check
 - cleanup
 - clamp
 - get text
 - Merge branch 'master' into 8347359.rta.api.tests
 - ... and 9 more: https://git.openjdk.org/jfx/compare/2b5b1132...25845fa8

Changes: https://git.openjdk.org/jfx/pull/1677/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1677&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8347359
  Stats: 1384 lines in 10 files changed: 1323 ins; 29 del; 32 mod
  Patch: https://git.openjdk.org/jfx/pull/1677.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1677/head:pull/1677

PR: https://git.openjdk.org/jfx/pull/1677