Clear listeners on process object when unloading.

The process object is created under node context, and it will live
through the reloading, so we are responsible for clearing the listeners
to make sure resources are not leaked.

renderer/api/lib/ipc.coffee

@@ -6,6 +6,9 @@ class Ipc extends EventEmitter
     process.on 'ATOM_INTERNAL_MESSAGE', (args...) =>
       @emit(args...)
 
+    window.addEventListener 'unload', (event) ->
+      process.removeAllListeners 'ATOM_INTERNAL_MESSAGE'
+
   send: (args...) ->
     ipc.send('ATOM_INTERNAL_MESSAGE', 'message', args...)