RFR: 8298644 JNI call of getCurrentComponent on a wrong thread [v6]

[Artem Semenov]

> [OutlineRowAccessibility currentAccessibleWithENV:] defines the getCurrentComponent method on the AccessibleContext instance of AccessibleJTreeNode class, however the call should go through CAccessibility so that it is executed on the Event Dispatch thread.

Artem Semenov has updated the pull request incrementally with one additional commit since the last revision:

  It is better to force the "ensureClassInitialized" as any other getters in this class. To make sure the field is up-to-date even if it was initialized on another thread.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/11670/files
  - new: https://git.openjdk.org/jdk/pull/11670/files/6efb419e..ed0752e8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11670&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11670&range=04-05

  Stats: 46 lines in 1 file changed: 23 ins; 23 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/11670.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11670/head:pull/11670

PR: https://git.openjdk.org/jdk/pull/11670