auto merge of #814 : jdm/servo/windowclose2, r=metajack

Fixed #671.

src/components/main/compositing/mod.rs

@@ -67,6 +67,10 @@ impl ScriptListener for CompositorChan {
         self.chan.send(InvalidateRect(id, rect));
     }
 
+    fn close(&self) {
+        self.chan.send(Exit);
+    }
+
 }
 
 /// Implementation of the abstract `RenderListener` interface.

src/components/msg/compositor_msg.rs

@@ -80,6 +80,7 @@ pub trait RenderListener {
 pub trait ScriptListener : Clone {
     fn set_ready_state(&self, ReadyState);
     fn invalidate_rect(&self, PipelineId, Rect<uint>);
+    fn close(&self);
 }
 
 /// The interface used by the quadtree to get info about LayerBuffers

src/components/script/script_task.rs

@@ -564,6 +564,7 @@ impl ScriptTask {
             }
             page.layout_chan.send(layout_interface::ExitMsg);
         }
+        self.compositor.close();
     }
 
     /// The entry point to document loading. Defines bindings, sets up the window and document