layout: Make animations work... more or less.

There's some maths I've done wrong, but it DOES animate some things, though
they're only triggered past the first restyle, and we probably have some
duplications where the animations arrive to layout.

Anyway, got to go.

components/layout_thread/lib.rs

@@ -1307,7 +1307,8 @@ impl LayoutThread {
                     self.profiler_metadata(),
                     self.time_profiler_chan.clone(),
                     || {
-                        animation::recalc_style_for_animations(flow_ref::deref_mut(&mut root_flow),
+                        animation::recalc_style_for_animations(&layout_context,
+                                                               flow_ref::deref_mut(&mut root_flow),
                                                                &mut animations)
                     });
         }