RFR: 8364777: RichTextArea: cursor over scrollbar

[Andy Goryachev]

Fixes the cursor over the content area vs other parts of the `RichTextArea` and `CodeArea`.

Root cause: styling wrong thing in modena.css.

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Commit messages:
 - cursor

Changes: https://git.openjdk.org/jfx/pull/1947/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1947&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8364777
  Stats: 9 lines in 1 file changed: 8 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jfx/pull/1947.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1947/head:pull/1947

PR: https://git.openjdk.org/jfx/pull/1947