Added Backbone.Collection.toJSON. Returns array of model's toJSON

backbone.js

@@ -329,6 +329,11 @@
     // The default model for a collection is just a **Backbone.Model**.
     // This should be overridden in most cases.
     model : Backbone.Model,
+    
+    // Return a array containing each model's toJSON result.
+    toJSON : function() {
+      return this.models.map(function(model){ return model.toJSON(); })
+    },
 
     // Add a model, or list of models to the set. Pass **silent** to avoid
     // firing the `added` event for every new model.