ART: More header cleanups

Pull out more dependencies through forward declarations.

Test: m test-art-host
Change-Id: I7d86726928937f788b956ec9eac91532d66d57ae
diff --git a/runtime/jit/jit_code_cache.h b/runtime/jit/jit_code_cache.h
index eea2771..9ecc876 100644
--- a/runtime/jit/jit_code_cache.h
+++ b/runtime/jit/jit_code_cache.h
@@ -29,7 +29,6 @@
 #include "jni.h"
 #include "method_reference.h"
 #include "oat_file.h"
-#include "object_callbacks.h"
 #include "profile_compilation_info.h"
 #include "safe_map.h"
 #include "thread_pool.h"
@@ -39,6 +38,7 @@
 class ArtMethod;
 class LinearAlloc;
 class InlineCache;
+class IsMarkedVisitor;
 class OatQuickMethodHeader;
 class ProfilingInfo;