Integrated: 8262750: Crash in J2DDemo after multiple plug/unplug of monitor

[Jayathirth D V]

Commit the commandQueue when we are overriding MTLContext to maintain proper state.

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Commit messages:
 - Commit when we override active context

Changes: https://git.openjdk.java.net/lanai/pull/207/files
 Webrev: https://webrevs.openjdk.java.net/?repo=lanai&pr=207&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262750
  Stats: 6 lines in 1 file changed: 6 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/lanai/pull/207.diff
  Fetch: git fetch https://git.openjdk.java.net/lanai pull/207/head:pull/207

PR: https://git.openjdk.java.net/lanai/pull/207