RFR: 8315883: Open source several Swing JToolbar tests [v4]

[Damon Nguyen]

> These are the tests being converted:
> 
> javax/swing/JToolBar/4138694/bug4138694.java
> javax/swing/JToolBar/4140421/bug4140421.java
> javax/swing/JToolBar/4196662/bug4196662.java
> javax/swing/JToolBar/4243930/bug4243930.java

Damon Nguyen has updated the pull request incrementally with one additional commit since the last revision:

  Remove redundant test comment and update exception

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15748/files
  - new: https://git.openjdk.org/jdk/pull/15748/files/88572ea0..faae15ed

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15748&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15748&range=02-03

  Stats: 5 lines in 1 file changed: 0 ins; 4 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/15748.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15748/head:pull/15748

PR: https://git.openjdk.org/jdk/pull/15748