RFR: 8252099: JavaFX does not render Myanmar script correctly

[Jose Pereda]

This PR allows rendering Myanmar script correctly, following up on https://bugs.openjdk.java.net/browse/JDK-8223558.

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Commit messages:
 - Allow rendering Myanmar script correctly

Changes: https://git.openjdk.java.net/jfx/pull/399/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=399&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8252099
  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/399.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/399/head:pull/399

PR: https://git.openjdk.java.net/jfx/pull/399