Revert "Initial check-in of an optimizing compiler."

g++ warnings turned into errors.

This reverts commit 68a5fefa90f03fdf5a238ac85c9439c6b03eae96.

Change-Id: I09bb95d9cc13764ca8a266c41af04801a34b9fd0
diff --git a/compiler/dex/backend.h b/compiler/dex/backend.h
index 596b3c9..01959b7 100644
--- a/compiler/dex/backend.h
+++ b/compiler/dex/backend.h
@@ -17,10 +17,10 @@
 #ifndef ART_COMPILER_DEX_BACKEND_H_
 #define ART_COMPILER_DEX_BACKEND_H_
 
-namespace art {
+#include "compiled_method.h"
+#include "arena_allocator.h"
 
-class ArenaAllocator;
-class CompiledMethod;
+namespace art {
 
 class Backend {
   public: