Add Handle/HandleScope and delete SirtRef.

Delete SirtRef and replaced it with Handle. Handles are value types
which wrap around StackReference*.

Renamed StackIndirectReferenceTable to HandleScope.

Added a scoped handle wrapper which wraps around an Object** and
restores it in its destructor.

Renamed Handle::get -> Get.

Bug: 8473721

Change-Id: Idbfebd4f35af629f0f43931b7c5184b334822c7a
diff --git a/runtime/gc/space/malloc_space.cc b/runtime/gc/space/malloc_space.cc
index 7493c19..ba46dcc 100644
--- a/runtime/gc/space/malloc_space.cc
+++ b/runtime/gc/space/malloc_space.cc
@@ -24,7 +24,7 @@
 #include "mirror/class-inl.h"
 #include "mirror/object-inl.h"
 #include "runtime.h"
-#include "sirt_ref-inl.h"
+#include "handle_scope-inl.h"
 #include "thread.h"
 #include "thread_list.h"
 #include "utils.h"