more argument checking

git-svn-id: https://wala.svn.sourceforge.net/svnroot/wala/trunk@1162 f5eafffb-2e1d-0410-98e4-8ec43c5233c4

com.ibm.wala.shrike/src/com/ibm/wala/shrikeBT/DupInstruction.java

@@ -94,7 +94,7 @@ public final class DupInstruction extends Instruction {
     return "Dup(" + size + "," + delta + ")";
   }
 
-  public void visit(Visitor v) throws IllegalArgumentException {
+  public void visit(Visitor v)  {
     if (v == null) {
       throw new IllegalArgumentException("illegal null visitor");
     }