8155951: VM crash in nsk/jvmti/RedefineClasses/StressRedefine: assert failed: Corrupted constant pool
8151066: assert(0 <= i && i < length()) failed: index out of bounds
Summary: lock classes for redefinition because constant pool merging isn't thread safe, use method constant pool because constant pool merging doesn't make equivalent cpCaches because of invokedynamic
Reviewed-by: shade, andrew