Remove object_utils.h.

Break into object_lock, field_helper and method_helper.
Clean up header files following this.
Also tidy some of the Handle code in response to compiler errors when resolving
the changes in this CL.

Change-Id: I73e63015a0f02a754d0866bfaf58208aebcaa295
diff --git a/compiler/driver/compiler_driver-inl.h b/compiler/driver/compiler_driver-inl.h
index e175d37..89295f2 100644
--- a/compiler/driver/compiler_driver-inl.h
+++ b/compiler/driver/compiler_driver-inl.h
@@ -20,12 +20,10 @@
 #include "compiler_driver.h"
 
 #include "dex/compiler_ir.h"
-#include "mirror/art_field.h"
+#include "field_helper.h"
 #include "mirror/art_field-inl.h"
-#include "mirror/art_method.h"
 #include "mirror/art_method-inl.h"
 #include "mirror/class_loader.h"
-#include "mirror/dex_cache.h"
 #include "mirror/dex_cache-inl.h"
 #include "mirror/art_field-inl.h"
 #include "scoped_thread_state_change.h"