RFR: 8239502: [TEST_BUG] Test javax/swing/text/FlowView/6318524/bug6318524.java never fails

[Alexey Ivanov]

The test is being moved from the closed to open. It's nearly a complete re-write of the original test.

I made the test headless by painting into image.

To detect failure, the test uses the position of the caret at the end of first line of the paragraph where the wrapping occurs.

I made sure that the updated test reproduces the original problem in [JDK-6318524](https://bugs.openjdk.java.net/browse/JDK-6318524). (There are some tweaks required to compile it with JDK 6.) The updated test fails when run with 6-b52. In fact, it also fails with 6-b53 up to 6-b76 where [JDK-6364882](https://bugs.openjdk.java.net/browse/JDK-6364882) is fixed.

The behaviour in 6-b76 coincides with that in the latest JDK.

[1] [JDK-6318524](https://bugs.openjdk.java.net/browse/JDK-6318524): Regression: views in paragraph are not children of Paragraph.Row is some cases
[2] [JDK-6364882](https://bugs.openjdk.java.net/browse/JDK-6364882): Last line of a paragraph should not be justified

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Commit messages:
 - 8239502: Make sure -saveAll saves all the images
 - 8239502: [TEST_BUG] Test javax/swing/text/FlowView/6318524/bug6318524.java never fails

Changes: https://git.openjdk.java.net/jdk/pull/5660/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5660&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8239502
  Stats: 194 lines in 1 file changed: 194 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5660.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5660/head:pull/5660

PR: https://git.openjdk.java.net/jdk/pull/5660