RFR: 8282548: Create a regression test for JDK-4330998 [v2]

[Manukumar V S]

> Create a regression test for [JDK-4330998](https://bugs.openjdk.java.net/browse/JDK-4330998)
> Context: Migrating tests from a closed tonga based test suite to open regression based one.
> 
> Issue tested:
> When calling JEditorPane.setText(null), the following exception is thrown:
> 
> java.lang.NullPointerException:
>         at java.io.StringReader.<init>(StringReader.java:38)
> 
> Testing:
> Java 1.4.0 -> Test Failed.
> $ ./j2sdk1.4.0/bin/java bug4330998Win
> java.lang.RuntimeException: Test failed, caught Exception java.lang.NullPointerException when calling text.setText(null)
>         at bug4330998Win.runTest(bug4330998Win.java:45)
>         at bug4330998Win.main(bug4330998Win.java:51)
> Exception in thread "main"
> 
> Java 1.4.1 -> Test Passed.
> $ ./j2sdk1.4.1/bin/java bug4330998Win
> Test passed

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

  Review comments fixed: Simplified the test, removed unwanted method

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7740/files
  - new: https://git.openjdk.java.net/jdk/pull/7740/files/f2e2bac8..990b6720

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7740&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7740&range=00-01

  Stats: 12 lines in 1 file changed: 0 ins; 10 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7740.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7740/head:pull/7740

PR: https://git.openjdk.java.net/jdk/pull/7740