RFR(XS): 8017531: 8010460 changes broke bytecodeInterpreter.cpp

[Lindenmaier, Goetz]

Hi,

This change repairs a small bug introduced by 8010460 in the
cppInterpreter.  In addition, it fixes two VERIFY_OOP()s that were called
on Method*.
http://cr.openjdk.java.net/~goetz/webrevs/8017531-fix_mh/

Please review this change.
I think this should be pushed into the main branch, not the
ppc64 staging repository.

Best regards,
  Goetz.