RFR: 801427: Remove ObjectClosure as base class for BoolObjectClosure

[Erik Helin]

Hi all,

this change remove ObjectClosure as the base class for BoolObjectClosure.

There is no good reason for BoolObjectClosure to derive from 
ObjectClosure, since all the users of a BoolObjectClosure will call the 
method do_object_b and not the method do_object (which is inherited from 
ObjectClosure). In fact, all classes deriving from BoolObjectClosure 
implements do_object by calling ShouldNotReachHere() or assert(false, 
"Call do_object_b instead") or something similar.

If there is need for a closure to be both an ObjectClosure and a 
BoolObjectClosure (there is no such closure in the code today), then 
that class can use multiple inheritance and derive from both 
ObjectClosure and BoolObjectClosure.

Webrev:
http://cr.openjdk.java.net/~ehelin/8014277/webrev.00/

Bug:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8014277

Testing:
JPRT

Thanks,
Erik