Added test for adding object literals as models

backbone/backbone-tests.ts

@@ -131,6 +131,11 @@ function test_collection() {
     var book1: Book = new Book({ title: "Title 1", author: "Mike" });
     books.add(book1);
 
+    // Objects can be added to collection by casting to model type.
+    // Compiler will check if object properties are valid for the cast.
+    // This gives better type checking than declaring an `any` overload.
+    books.add(<Book>{ title: "Title 2", author: "Mikey" });
+
     var model: Book = book1.collection.first();
     if (model !== book1) {
         throw new Error("Error");