RFR: 8281738: Create a regression test for checking the 'Space' key activation of focused Button [v2]

[Manukumar V S]

> This test verifies in all platforms and in all 'Look and Feels' that pressing the 'Space' key generates ActionEvent on focused Button or not.

Manukumar V S has updated the pull request incrementally with one additional commit since the last revision:

  Fixed review comments: waitForIdle() added after frame creation and waits until button gains focus

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7460/files
  - new: https://git.openjdk.java.net/jdk/pull/7460/files/539b0eb8..eb6adc3d

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7460&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7460&range=00-01

  Stats: 22 lines in 1 file changed: 19 ins; 1 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7460.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7460/head:pull/7460

PR: https://git.openjdk.java.net/jdk/pull/7460