Replacing the testcase.jar added by JDK-8211123 by an in memory compilation would simplify the test's dependency.

A version of what could be used exists in github:
https://github.com/tstuefe/ojdk-repros/tree/master/src/test3

The OpenJDK library also provides InMemoryCompilation in the test library (test/jdk/test/lib/compiler/*) and could also be used.

This bug is about replacing the .jar with an in memory solution instead of an explicit .jar dependency.