bug in InstructionList: shouldn't dispose Instruction's on delete

I'm ending up with an InstructionList that contains a goto Instruction
whose target is null, and the reason for that is the call to dispose()
on line 737 of InstructionList.java.  I believe lines 736 and 737 should
just be removed.  An Instruction can be the instruction for multiple
handles, so deleting one should not invalidate the instruction of the
other handles.  I can provide sample code to demonstrate what i'm
talking about, but I think it would go something like this:

InstructionList il = new InstructionList();
InstructionHandle nop = il.append(new NOP());
InstructionHandle goto1 = il.append(new GOTO(nop));
InstructionHandle goto2 = il.append(new GOTO(nop));
il.delete(goto2);
if(((GOTO)goto1.getInstruction()).getTarget() == null)
   panic("It really should be nop");

-- 
"I say to you that the VCR is to the American film
producer and the American public as the Boston
strangler is to the woman home alone."
         -Jack Valenti, President, Motion Picture
          Association of America, Inc., before
          The House Subcommittee on Courts, Civil
          Liberties, and The Administration of
          Justice, August, 1982,
          http://cryptome.org/hrcw-hear.htm