Bug 1430018 - Don't use nsWindow::IsX11Display() as it's not implemented, r=jhorak

MozReview-Commit-ID: cR6q3fBhTo

--HG--
extra : rebase_source : ab137c3fe504555155f998b7d7e4332f9f802fae

widget/gtk/WindowSurfaceProvider.cpp

@@ -56,7 +56,7 @@ void WindowSurfaceProvider::Initialize(
 #ifdef MOZ_WAYLAND
 void WindowSurfaceProvider::Initialize(nsWindow *aWidget)
 {
-  MOZ_ASSERT(!aWidget->IsX11Display(),
+  MOZ_ASSERT(aWidget->GetWaylandDisplay(),
              "We are supposed to have a Wayland display!");
 
   mWidget = aWidget;