fix for bug 130135 - remove "virtual" from nsObserverList because it doesn't have virtual methods

(saves 4 bytes per list)
r=dougt, sr=darin, a=roc+moz

xpcom/ds/nsObserverList.h

@@ -62,7 +62,7 @@ class nsObserverList
 {
 public:
   nsObserverList();
-  virtual    ~nsObserverList();
+  ~nsObserverList();
 
   nsresult AddObserver(nsIObserver* anObserver, PRBool ownsWeak);
   nsresult RemoveObserver(nsIObserver* anObserver);