Adjust early return behavior for fullscreen, maximized, and minimized…

… window states in the BiDi specification (#844)

index.bs

@@ -2239,7 +2239,7 @@ To <dfn>set the client window state</dfn> given |window| and |state|:
 
 1. Let |current state| be [=get the client window state=] with |window|.
 
-1. If |current state| is equal to |state|, return [=success=] with data null.
+1. If |current state| is "<code>fullscreen</code>", "<code>maximized</code>", or "<code>minimized</code>" and is equal to |state|, return [=success=] with data null.
 
 1. In the following list of conditions and associated steps, run the first set of steps for which the associated condition is true: