Fix leak regression from yesterday: derived classes use NS_IMPL_RELEASE_INHERITED, which relies on destructor being virtual. r+sr=bzbarsky a=brendan b=283489

xpcom/ds/nsHashPropertyBag.h

@@ -56,6 +56,7 @@ class NS_COM nsHashPropertyBag : public nsIWritablePropertyBag
 {
 public:
     nsHashPropertyBag() { }
+    virtual ~nsHashPropertyBag() {}
 
     nsresult Init();