[resize-observer-1] Invoke callback with observer as 2nd argument and this value

Author: shvaikalesh

resize-observer-1/Overview.bs

@@ -506,7 +506,7 @@ To broadcast active resize observations for a |document|, run these steps:
 
         5. Set |shallowestTargetDepth| to |targetDepth| if |targetDepth| < |shallowestTargetDepth|
 
-    4. Invoke |observer|.{{ResizeObserver/[[callback]]}} with |entries|.
+    4. Invoke |observer|.{{ResizeObserver/[[callback]]}} with |entries| as the first argument and |observer| as the second argument and <a>callback this value</a>. If this throws an exception, <a>report the exception</a>.
 
     5. Clear |observer|.{{ResizeObserver/[[activeTargets]]}}.