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/scoped_thread_state_change.h b/runtime/scoped_thread_state_change.h
index 7698d6a..dbd961f 100644
--- a/runtime/scoped_thread_state_change.h
+++ b/runtime/scoped_thread_state_change.h
@@ -25,7 +25,7 @@
 
 // Scoped change into and out of a particular state. Handles Runnable transitions that require
 // more complicated suspension checking. The subclasses ScopedObjectAccessUnchecked and
-// ScopedObjectAccess are used to handle the change into Runnable to get direct access to objects,
+// ScopedObjectAccess are used to handle the change into Runnable to Get direct access to objects,
 // the unchecked variant doesn't aid annotalysis.
 class ScopedThreadStateChange {
  public: