Bug 1161831 - Stop using threaddsafe ISupports for nsResProtocolHandler. r=billm

As far as I can tell, this thing isn't threadsafe at all.

netwerk/protocol/res/nsResProtocolHandler.h

@@ -27,7 +27,7 @@ public:
 class nsResProtocolHandler final : public nsIResProtocolHandler, public nsSupportsWeakReference
 {
 public:
-    NS_DECL_THREADSAFE_ISUPPORTS
+    NS_DECL_ISUPPORTS
     NS_DECL_NSIPROTOCOLHANDLER
     NS_DECL_NSIRESPROTOCOLHANDLER