RFR: 8269593: Different fontname on macos

[Johan Vos]

Make sure the returned fullName of a created font matches the requested name. Since the name is used as a key/identifier in some cases, some internal code relies on this.
Added a test to check the case of "System Font Regular" on MacOS, which fails before and succeeds after the patch.

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Commit messages:
 - Fix for JDK-8269593

Changes: https://git.openjdk.java.net/jfx/pull/553/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=553&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8269593
  Stats: 25 lines in 3 files changed: 24 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/553.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/553/head:pull/553

PR: https://git.openjdk.java.net/jfx/pull/553