Fixes warning showing up with the new SpiderMonkey.

The changed return value isn't related but returning false makes more
sense there IMO.

Refs #2372

This was SVN commit r14863.

binaries/data/mods/public/gui/session/messages.js

@@ -33,6 +33,9 @@ function handleNotifications()
 
 	if (!notification)
 		return;
+	
+	if (notification.type === undefined)
+		notification.type = "text";
 
 	// Handle chat notifications specially
 	if (notification.type == "chat")
@@ -107,7 +110,7 @@ function handleNotifications()
 			}
 		}
 	}
-	else
+	else if (notification.type == "text")
 	{
 		// Only display notifications directed to this player
 		if (notification.player == Engine.GetPlayerID())
@@ -121,6 +124,10 @@ function handleNotifications()
 				displayNotifications();
 		}
 	}
+	else
+	{
+		warn("notification of unknown type!");
+	}
 }
 
 function removeOldNotifications()

binaries/data/mods/public/simulation/components/GuiInterface.js

@@ -807,7 +807,7 @@ GuiInterface.prototype.GetNextNotification = function()
 	if (this.notifications.length)
 		return this.notifications.pop();
 	else
-		return "";
+		return false;
 };
 
 GuiInterface.prototype.GetAvailableFormations = function(player, data)