RFR: 8282857: Create a regression test for JDK-4702690

[Srinivas Mandalika]

Create a regression test for [JDK-4702690](https://bugs.openjdk.java.net/browse/JDK-4702690)

In many cases in Swing it is possible to easily programatically determine that a JScrollBar (or two) is scrolling some JPanel (the cannonical case is a JScrollPane).
In these cases, when accessibility support is instantiated (e.g. the AccessibleJScrollBar is created), a Controller_For and Controled_By relation should be instantiated between the AccessibleJScrollBar and the AccessibleJPanel that the JScrollBar and JPanel are associated with.

This allows various assistive technologies, especially voice-recognition technologies, to better interact with scrolling items.

The test put up validates that the target object for these properties(CONTROLLED_BY, CONTROLLED_FOR) are set appropriately for JScrollPane and JScrollBar.

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

Commit messages:
 - 8282857: Create a regression test for JDK-4702690

Changes: https://git.openjdk.java.net/jdk/pull/7753/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7753&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8282857
  Stats: 106 lines in 1 file changed: 106 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7753.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7753/head:pull/7753

PR: https://git.openjdk.java.net/jdk/pull/7753