Tying loose ends: clamping start/end positions in the `StyledTextModel` mutation operations to avoid problems down the road.
------------- Commit messages: - fix - Merge remote-tracking branch 'origin/master' into 8373193.beyond - tests Changes: https://git.openjdk.org/jfx/pull/2001/files Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=2001&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8373193 Stats: 20 lines in 2 files changed: 17 ins; 0 del; 3 mod Patch: https://git.openjdk.org/jfx/pull/2001.diff Fetch: git fetch https://git.openjdk.org/jfx.git pull/2001/head:pull/2001 PR: https://git.openjdk.org/jfx/pull/2001
