Linearize the graph before creating live ranges.

Change-Id: I02eb5671e3304ab062286131745c1366448aff58
diff --git a/compiler/optimizing/graph_visualizer.h b/compiler/optimizing/graph_visualizer.h
index 433d55d..2b88e65 100644
--- a/compiler/optimizing/graph_visualizer.h
+++ b/compiler/optimizing/graph_visualizer.h
@@ -42,6 +42,12 @@
                    const DexCompilationUnit& cu);
 
   /**
+   * Version of `HGraphVisualizer` for unit testing, that is when a
+   * `DexCompilationUnit` is not available.
+   */
+  HGraphVisualizer(std::ostream* output, HGraph* graph, const char* name);
+
+  /**
    * If this visualizer is enabled, emit the compilation information
    * in `output_`.
    */