RFR: 5074006: Swing JOptionPane shows </html> tag as a string after newline [v3]

[Prasanta Sadhukhan]

> If JOptionPane's message contains both linefeed/cursor return and HTML tag ie, **<html\>" + "This is a test\n" + "</html\>**,
> then  "</html\>" will be shown in the JOptionPane dialog box because after every new line it creates a new messageComponent so the characters after the newline ie "</html\>"tag will be considered as a new JLabel string and displayed.
> 
> Fix is to ignore closing html tag if appearing after newline from the displayed string.

Prasanta Sadhukhan has updated the pull request incrementally with one additional commit since the last revision:

  Add comments

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Changes:
  - all: https://git.openjdk.org/jdk/pull/10081/files
  - new: https://git.openjdk.org/jdk/pull/10081/files/2b00d425..c6901154

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10081&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10081&range=01-02

  Stats: 7 lines in 1 file changed: 6 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/10081.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10081/head:pull/10081

PR: https://git.openjdk.org/jdk/pull/10081