RFR: 8274465: Fix javax/swing/text/ParagraphView/6364882/bug6364882.java failures

[Alexey Ivanov]

I made the test and its assertions more flexible in regards to the font size and to the number of lines.

The test still requires there are at least four lines so that the text is wrapped before the first hard line break; thus at least one line of text is justified. This pre-requisite gets broken if `font-size: 4pt` property is added to the `style` attribute in my local environment. I also ran the test with a few larger font sizes, the updated test passes successfully.

I made sure the image is saved if any exception gets thrown from `checkJustification`, which wasn't the case.

This PR replaces #5744.

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

Commit messages:
 - 8274465: Some cleanup
 - 8274465: Make the test more flexible to the number of lines and font-size
 - 8274465: Save the image of editorPane on any exception

Changes: https://git.openjdk.java.net/jdk/pull/5761/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5761&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274465
  Stats: 64 lines in 1 file changed: 20 ins; 7 del; 37 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5761.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5761/head:pull/5761

PR: https://git.openjdk.java.net/jdk/pull/5761