RFR: 8327471: RTLTextFlowCharacterIndexTest fails on Linux

[Karthik P K]

Because of the difference in the size of characters in default fonts in different OS, 2 tests were failing in `RTLTextFlowCharacterIndexTest`.

Increased the scene width to accommodate all the characters as required for the test to validate HitInfo values in all the platforms.

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Commit messages:
 - RTL text test fix

Changes: https://git.openjdk.org/jfx/pull/1399/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1399&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8327471
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jfx/pull/1399.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1399/head:pull/1399

PR: https://git.openjdk.org/jfx/pull/1399