RFR: 8269026: PasswordField doesn't render bullet character on Android

[Jose Pereda]

This PR modifies the PasswordField's bullet character used on Android, as the current unicode code is not supported for most fonts, including Roboto.

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Commit messages:
 - Modify bullet character for PasswordField on Android

Changes: https://git.openjdk.java.net/jfx/pull/537/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=537&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8269026
  Stats: 12 lines in 1 file changed: 12 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/537.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/537/head:pull/537

PR: https://git.openjdk.java.net/jfx/pull/537