Revert "Introduce a class to implement optimization passes."

This reverts commit bf9cd7ba2118a75f5aa9b56241c4d5fa00dedeb8.

Change-Id: I0a483446666c9c24c45925a5fc199debdefd8b3e
diff --git a/compiler/optimizing/graph_visualizer.h b/compiler/optimizing/graph_visualizer.h
index e45bba3..6e2c6fd 100644
--- a/compiler/optimizing/graph_visualizer.h
+++ b/compiler/optimizing/graph_visualizer.h
@@ -61,7 +61,7 @@
    * If this visualizer is enabled, emit the compilation information
    * in `output_`.
    */
-  void DumpGraph(const char* pass_name) const;
+  void DumpGraph(const char* pass_name);
 
  private:
   std::ostream* const output_;