Angular IPromise interop with platform Promise.

Angular promises support `.then()` chaining of functions that return
arbitrary `then()`able values.
    https://docs.angularjs.org/api/ng/service/$q#the-promise-api

This change updates the definition of `ng.IPromise.then()` to match that
by overloading the function to handle `PromiseLike` values.

types/angular/angular-tests.ts

@@ -294,6 +294,14 @@ foo.then((x) => {
     x.toFixed();
 });
 
+namespace TestPromiseInterop {
+    declare const promiseInterop: ng.IPromise<number>;
+    const ngStringPromise: ng.IPromise<string> =
+        promiseInterop.then((num) => Promise.resolve(String(num)));
+    const caughtStringPromise: ng.IPromise<string|number> =
+        promiseInterop.catch((reason) => Promise.resolve('oh noes'));
+}
+
 // $q signature tests
 namespace TestQ {
     interface AbcObject {

types/angular/index.d.ts

@@ -1197,6 +1197,15 @@ declare namespace angular {
          * the `notifyCallback` method. The promise can not be resolved or rejected from the
          * `notifyCallback` method.
          */
+        then<TResult1 = T, TResult2 = never>(
+            successCallback?:
+                | ((value: T) => PromiseLike<never> | PromiseLike<TResult1> | TResult1)
+                | null,
+            errorCallback?:
+                | ((reason: any) => PromiseLike<never> | PromiseLike<TResult2> | TResult2)
+                | null,
+            notifyCallback?: (state: any) => any
+        ): IPromise<TResult1 | TResult2>;
         then<TResult1 = T, TResult2 = never>(
             successCallback?:
                 | ((value: T) => IPromise<never> | IPromise<TResult1> | TResult1)
@@ -1210,6 +1219,11 @@ declare namespace angular {
         /**
          * Shorthand for promise.then(null, errorCallback)
          */
+        catch<TResult = never>(
+            onRejected?:
+                | ((reason: any) => PromiseLike<never> | PromiseLike<TResult> | TResult)
+                | null
+        ): IPromise<T | TResult>;
         catch<TResult = never>(
             onRejected?:
                 | ((reason: any) => IPromise<never> | IPromise<TResult> | TResult)

types/angular/tsconfig.json

@@ -11,7 +11,8 @@
         "lib": [
             "es5",
             "dom",
-            "es2015.iterable"
+            "es2015.iterable",
+            "es2015.promise"
         ],
         "noImplicitAny": false,
         "noImplicitThis": false,
@@ -25,4 +26,4 @@
         "noEmit": true,
         "forceConsistentCasingInFileNames": true
     }
-}
+}