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/oat_file.h b/runtime/oat_file.h
index 8477723..e5dc53c 100644
--- a/runtime/oat_file.h
+++ b/runtime/oat_file.h
@@ -153,7 +153,7 @@
       return type_;
     }
 
-    // get the OatMethod entry based on its index into the class
+    // Get the OatMethod entry based on its index into the class
     // defintion. direct methods come first, followed by virtual
     // methods. note that runtime created methods such as miranda
     // methods are not included.