Linearize the graph before creating live ranges.

Change-Id: I02eb5671e3304ab062286131745c1366448aff58
diff --git a/compiler/optimizing/liveness_test.cc b/compiler/optimizing/liveness_test.cc
index d665ab9..53e7bbe 100644
--- a/compiler/optimizing/liveness_test.cc
+++ b/compiler/optimizing/liveness_test.cc
@@ -35,6 +35,7 @@
   ASSERT_NE(graph, nullptr);
   graph->BuildDominatorTree();
   graph->TransformToSSA();
+  graph->FindNaturalLoops();
   SsaLivenessAnalysis liveness(*graph);
   liveness.Analyze();