Fixed RefCounting bug where following links would decrement the WebShell ref count :-(

docshell/base/nsWebShell.cpp

@@ -1440,6 +1440,7 @@ nsWebShell::GetTarget(const PRUnichar* aName)
   nsIWebShell* target = nsnull;
 
   if (0 == name.Length()) {
+    NS_ADDREF_THIS();
     return this;
   }
   

webshell/src/nsWebShell.cpp

@@ -1440,6 +1440,7 @@ nsWebShell::GetTarget(const PRUnichar* aName)
   nsIWebShell* target = nsnull;
 
   if (0 == name.Length()) {
+    NS_ADDREF_THIS();
     return this;
   }