Revert "Introduce a class to implement optimization passes."

This reverts commit bf9cd7ba2118a75f5aa9b56241c4d5fa00dedeb8.

Change-Id: I0a483446666c9c24c45925a5fc199debdefd8b3e
diff --git a/compiler/optimizing/graph_visualizer.cc b/compiler/optimizing/graph_visualizer.cc
index fabae21..0fb4737 100644
--- a/compiler/optimizing/graph_visualizer.cc
+++ b/compiler/optimizing/graph_visualizer.cc
@@ -307,7 +307,7 @@
   printer.EndTag("compilation");
 }
 
-void HGraphVisualizer::DumpGraph(const char* pass_name) const {
+void HGraphVisualizer::DumpGraph(const char* pass_name) {
   if (!is_enabled_) {
     return;
   }