angularjs: Reverting to using stronger signatures for IPromise. With tests for that.

angularjs/angular-tests.ts

@@ -185,22 +185,28 @@ mod.value(My.Namespace);
 // Promise signature tests
 var foo: ng.IPromise<number>;
 foo.then((x) => {
-    // x is infered to be a number. Expected
+    // x is inferred to be a number
     return "asdf";
 }).then((x) => {
-    // x is inferred to be string. Awesome
+    // x is inferred to be string
     x.length;
     return 123;
 }).then((x) => {
-    // x is infered to be a number. Awesomer
+    // x is infered to be a number
     x.toFixed();
     return;
 }).then((x) => {
-    // x is infered to be void. Sounds good. 
-    // Of course you cannot use x here (typescript will prevent you)
+    // x is infered to be void
+    // Typescript will prevent you to actually use x as a local variable
     // Try object:
     return { a: 123 };
 }).then((x) => {
-    // Still works
+    // Object is inferred here
     x.a = 123;
+    //Try a promise 
+    var y: ng.IPromise<number>;
+    return y; 
+}).then((x) => {
+    // x is infered to be a number, which is the resolved value of a promise 
+    x.toFixed();
 });

angularjs/angular.d.ts

@@ -406,7 +406,8 @@ declare module ng {
     }
 
     interface IPromise<T> {
-        then(successCallback: (promiseValue: T) => any, errorCallback?: (reason: any) => any): IPromise<any>;
+        then<TResult>(successCallback: (promiseValue: T) => IPromise<TResult>, errorCallback?: (reason: any) => any): IPromise<TResult>;
+        then<TResult>(successCallback: (promiseValue: T) => TResult, errorCallback?: (reason: any) => TResult): IPromise<TResult>;
     }
 
     interface IDeferred<T> {