RFR: 8282640: Create a test for JDK-4740761

[Srinivas Mandalika]

Create a test for [JDK-4740761](https://bugs.openjdk.java.net/browse/JDK-4740761)

The issue observed is in a JFrame with a JTextField and a JScrollPane which contains focused component. When the JScrollPane was
is removed from its parent, focus stays with the the scroller
of the removed JScrollPane, instead of moving to the TextField.

The test verifies the same - i.e. it verifies that the removal of the scrollpane moves the focus to the JTextField present in the JFrame.

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Commit messages:
 - 8282640: Create a test for JDK-4740761
 - 8282640: Create a test for JDK-4740761
 - 8282640: Create a test for JDK-4740761

Changes: https://git.openjdk.java.net/jdk/pull/7686/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7686&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8282640
  Stats: 118 lines in 1 file changed: 118 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7686.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7686/head:pull/7686

PR: https://git.openjdk.java.net/jdk/pull/7686