Revert "Merge pull request #2819 from bjwbell/iframe-layers"

This reverts commit 0200b61f71, reversing
changes made to ca96821902.

src/components/script/page.rs

@@ -319,7 +319,7 @@ impl Page {
                 self.join_layout();
 
                 // Tell the user that we're performing layout.
-                compositor.set_ready_state(self.id, PerformingLayout);
+                compositor.set_ready_state(PerformingLayout);
 
                 // Layout will let us know when it's done.
                 let (join_chan, join_port) = channel();