Bug 1114299 - Be more strict about which window chromeFlags we compute from content. r=smaug

We don't ever want to accept "private", "non-private", "remote" or "non-remote" from the
content process. We only let the parent decide when to open those types of windows.

docshell/base/nsDocShell.cpp

@@ -9837,13 +9837,9 @@ nsDocShell::InternalLoad(nsIURI* aURI,
       if (aURI) {
         aURI->GetSpec(spec);
       }
-      nsAutoString features;
-      if (mInPrivateBrowsing) {
-        features.AssignLiteral("private");
-      }
       rv = win->OpenNoNavigate(NS_ConvertUTF8toUTF16(spec),
                                name,  // window name
-                               features,
+                               EmptyString(), // Features
                                getter_AddRefs(newWin));
 
       // In some cases the Open call doesn't actually result in a new