RFR: vbox/vunbox should throw ClassCastException if target type is invalid

[Roland Westrelin]

> http://cr.openjdk.java.net/~thartmann/valhalla/vt_prototype/webrev.19/

 610   // Check if the class of the source is a subclass of the value-capable class
 611   // corresponding to the target.
 612   // TOOD: Implement profiling of vunbox bytecodes to enable type speculation.
 613   if (target_vcc_klass == NULL || !target_vcc_klass->is_subclass_of(source_type->klass())) {

The comment says class of the source subclass target's vcc but the code
does the opposite check?

Roland.