RFR: 8281535: Create a regression test for JDK-4670051

[Manukumar V S]

Create a regression test for [JDK-4670051](https://bugs.openjdk.java.net/browse/JDK-4670051) which checks whether JSpinner with a SpinnerDateModel exactly spins the field where cursor is there.
I have updated the testing details in the comment section of JDK-8281535.

-------------

Commit messages:
 - 8281535: Create a regression test for JDK-4670051

Changes: https://git.openjdk.java.net/jdk/pull/7404/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7404&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8281535
  Stats: 302 lines in 1 file changed: 302 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7404.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7404/head:pull/7404

PR: https://git.openjdk.java.net/jdk/pull/7404