Added support for binding to multiple observable objects (properties).

data/observable/observable.d.ts

@@ -99,6 +99,11 @@ declare module "data/observable" {
          */
         notify(data: EventData): void;
 
+        /**
+         * Notifies all the registered listeners for the property change event.
+         */
+        notifyPropertyChange(propertyName: string, newValue: any): void;
+
         /**
          * Checks whether a listener is registered for the specified event name.
          * @param eventName The name of the event to check for.

data/observable/observable.ts

@@ -91,6 +91,10 @@ export class Observable implements definition.Observable {
         }
     }
 
+    public notifyPropertyChange(propertyName: string, newValue: any) {
+        this.notify(this._createPropertyChangeData(propertyName, newValue));
+    }
+
     public set(name: string, value: any) {
         // TODO: Parameter validation
         if (this[name] === value) {
@@ -122,8 +126,8 @@ export class Observable implements definition.Observable {
 
         var i;
         var entry: ListenerEntry;
-
-        for (i = 0; i < observers.length; i++) {
+        var observersLength = observers.length;
+        for (i = 0; i < observersLength; i++) {
             entry = observers[i];
             if (entry.thisArg) {
                 entry.callback.apply(entry.thisArg, [data]);