ART: Small iwyu

Forward-declare code item accessors in ArtMethod.

Test: mmma art
Change-Id: Ib4b2f274130416ee07e873ec32cef98d10c95838
diff --git a/runtime/art_method.h b/runtime/art_method.h
index d1647cc..c865433 100644
--- a/runtime/art_method.h
+++ b/runtime/art_method.h
@@ -28,9 +28,7 @@
 #include "base/enums.h"
 #include "base/macros.h"
 #include "base/runtime_debug.h"
-#include "dex/code_item_accessors.h"
 #include "dex/dex_file_structs.h"
-#include "dex/dex_instruction_iterator.h"
 #include "dex/modifiers.h"
 #include "dex/primitive.h"
 #include "dex/signature.h"
@@ -41,6 +39,9 @@
 
 namespace art {
 
+class CodeItemDataAccessor;
+class CodeItemDebugInfoAccessor;
+class CodeItemInstructionAccessor;
 class DexFile;
 template<class T> class Handle;
 class ImtConflictTable;