RFR (L): 8225325: Add tests for redefining a class' private method during resolution of the bootstrap specifier

[serguei.spitsyn at oracle.com]

Please, review 2 new tests for the test enhancement:
   https://bugs.openjdk.java.net/browse/JDK-8225325

Webrev:
http://cr.openjdk.java.net/~sspitsyn/webrevs/2019/8225325-jvmti-redef-tests.1/


Summary:
   The tests were originally developed by Lois.
   So, I need to be counted as a reviewer. :)
   Lois already looked at the tests and approved their refactoring.

   These tests were not pushed the following bug was hit:
     https://bugs.openjdk.java.net/browse/JDK-8191496

   It looked like that bug was somehow caused by the InMemoryJavaCompiler
   framework that was used for testing. The issue disappeared after the 
tests
   were re-written to use a modern testing technique where the redefined
   classes are present in separate files instead of Java strings.

   I've just closed the 8191496 as NAI.

Thanks,
Serguei