RFR: 8264297: Create implementation for NSAccessibilityProgressIndicator protocol peer

[Alexander Zuev]

Add component accessibility peer

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Commit messages:
 - JDK-8264297: Create implementation for NSAccessibilityProgressIndicator protocol peer

Changes: https://git.openjdk.java.net/jdk/pull/6462/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6462&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8264297
  Stats: 48 lines in 3 files changed: 46 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6462.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6462/head:pull/6462

PR: https://git.openjdk.java.net/jdk/pull/6462