Add validate object, clean up stack indirect reference table.

Change-Id: Ifb329ae7d3bede3e95d48e6761cee1412a33d867
diff --git a/src/globals.h b/src/globals.h
index 777cfd6..2fb0225 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -35,6 +35,9 @@
 // Required stack alignment
 const int kStackAlignment = 16;
 
+// Required object alignment
+const int kObjectAlignment = 8;
+
 // System page size.  Normally you're expected to get this from
 // sysconf(_SC_PAGESIZE) or some system-specific define (usually
 // PAGESIZE or PAGE_SIZE).  If we use a simple compile-time constant