It's available. It looks like updating the version has resolved my issue which I believe would have been similar to yours. I assume your problem is some variation of java.lang.VerifyError: Expecting a stackmap frame.
At the time of writing version 3.19 of Javassist is available. PowerMock 1.5.1 is also updated to use Javassist 3.18 GA.
Alternative fixes
Besides the upgrade, one of the other recommended solutions is the use of the JVM argument -XX:-UseSplitVerifier from a combination of
here on Java 7 stack map issues and
here on the PowerMock issues registry about java.lang.VerifyError (which you have linked to).
Implementations Of Alternative Fixes
In IntelliJ I've added the -UseSplitVerifier to my JUnit runner but there are also recommendations about adding it to the Maven Surefire plugin in your build in order to make the solution portable such as is recommended in this post.