RFR: 8315883: Open source several Swing JToolbar tests [v2]

[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:

  Review comments update

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15748/files
  - new: https://git.openjdk.org/jdk/pull/15748/files/a8c8176c..a1755a88

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15748&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15748&range=00-01

  Stats: 15 lines in 3 files changed: 2 ins; 8 del; 5 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