RFR: 8295707: Create a regression test for JDK-7184401

[Srinivas Mandalika]

8295707: Create a regression test for JDK-7184401

JDK-7184401 - JDk7u6 : Missing main menu bar in Netbeans after fix for 7162144
As indicated in the above bug's description, it got introduced due to a fix for [JDK-7162144](https://bugs.openjdk.java.net/browse/JDK-7162144). The test below recreates a standalone test to mimic the failure reported in Netbeans in [JDK-7184401](https://bugs.openjdk.java.net/browse/JDK-7184401) and verifies that it is working as expected after it got fixed.( Via [JDK-7189350](https://bugs.openjdk.java.net/browse/JDK-7189350))

The Test attempts to reproduce specific behavior of NetBeans at the certain toolbar creation stage. Widgets are created on EDT; Another code posts some events to them on EDT; From another thread some code calls explicitlyedt.interrupt().
Before this got fixed, events from a second code got lost.

This review is for migrating tests from a closed test suite to open.
Testing:
1.Tested the code on jdk7u6 to reproduce the issue - the UI hangs when run on this build.
2. Tested the code on jdk7u361 b01 to validate the fix - the test passed.
3.Mach5 Testing(40 times per platform) in macos x64, linux x64 and windows x64 - the .results are clean

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Commit messages:
 - Minor Code Cleanups
 - 8295707: Create a regression test for JDK-7184401

Changes: https://git.openjdk.org/jdk/pull/10784/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10784&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8295707
  Stats: 107 lines in 1 file changed: 107 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/10784.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10784/head:pull/10784

PR: https://git.openjdk.org/jdk/pull/10784