8188223: IfNode::range_check_trap_proj() should handler dying subgraph with single if proj

Reviewed-by: kvn

src/share/vm/opto/ifnode.cpp

@@ -453,6 +453,9 @@ static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
 // offset.  Return 2 if we had to negate the test.  Index is NULL if the check
 // is versus a constant.
 int IfNode::is_range_check(Node* &range, Node* &index, jint &offset) {
+  if (outcnt() != 2) {
+    return 0;
+  }
   Node* b = in(1);
   if (b == NULL || !b->is_Bool())  return 0;
   BoolNode* bn = b->as_Bool();