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/mirror/art_field.cc b/runtime/mirror/art_field.cc
index 8eb30f9..86c5c3f 100644
--- a/runtime/mirror/art_field.cc
+++ b/runtime/mirror/art_field.cc
@@ -29,7 +29,7 @@
 namespace art {
 namespace mirror {
 
-// TODO: get global references for these
+// TODO: Get global references for these
 Class* ArtField::java_lang_reflect_ArtField_ = NULL;
 
 ArtField* ArtField::FromReflectedField(const ScopedObjectAccess& soa, jobject jlr_field) {