Clean backport of RichTextArea clamp and getText fix to the jfx24 stabilization branch.
------------- Commit messages: - Backport 2b5b11320087de9b7bb6f330236a5c15eb4cabea Changes: https://git.openjdk.org/jfx/pull/1688/files Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1688&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8348736 Stats: 220 lines in 7 files changed: 156 ins; 51 del; 13 mod Patch: https://git.openjdk.org/jfx/pull/1688.diff Fetch: git fetch https://git.openjdk.org/jfx.git pull/1688/head:pull/1688 PR: https://git.openjdk.org/jfx/pull/1688
