Implement default traversals in CFG & SSA graph checkers.

- Check CFG graphs using an insertion order traversal.
- Check SSA form graphs using a reverse post-order traversal.

Change-Id: Ib9062599bdbf3c17b9f213b743274b2d71a9fa90
diff --git a/compiler/optimizing/constant_propagation_test.cc b/compiler/optimizing/constant_propagation_test.cc
index 342777a..ff44805 100644
--- a/compiler/optimizing/constant_propagation_test.cc
+++ b/compiler/optimizing/constant_propagation_test.cc
@@ -62,7 +62,7 @@
   ASSERT_EQ(expected_after_dce, actual_after_dce);
 
   SSAChecker ssa_checker(&allocator, graph);
-  ssa_checker.VisitInsertionOrder();
+  ssa_checker.Run();
   ASSERT_TRUE(ssa_checker.IsValid());
 }