Refactor ArenaBitVector to create more general BitVector

Change-Id: Ib26f2884de9ce7d620048bdf5ed6dec639622e41
diff --git a/compiler/dex/ssa_transformation.cc b/compiler/dex/ssa_transformation.cc
index eb0d412..b6c8922 100644
--- a/compiler/dex/ssa_transformation.cc
+++ b/compiler/dex/ssa_transformation.cc
@@ -183,7 +183,7 @@
   ClearAllVisitedFlags();
   std::vector<std::pair<BasicBlock*, ArenaBitVector::Iterator*> > work_stack;
   bb->visited = true;
-  work_stack.push_back(std::make_pair(bb, new (arena_) ArenaBitVector::Iterator(bb->i_dominated)));
+  work_stack.push_back(std::make_pair(bb, bb->i_dominated->GetIterator()));
   while (!work_stack.empty()) {
     const std::pair<BasicBlock*, ArenaBitVector::Iterator*>& curr = work_stack.back();
     BasicBlock* curr_bb = curr.first;
@@ -196,7 +196,7 @@
       BasicBlock* new_bb = GetBasicBlock(bb_idx);
       new_bb->visited = true;
       work_stack.push_back(
-          std::make_pair(new_bb, new (arena_) ArenaBitVector::Iterator(new_bb->i_dominated)));
+          std::make_pair(new_bb, new_bb->i_dominated->GetIterator()));
     } else {
       // no successor/next
       if (curr_bb->id != NullBasicBlockId) {