fix(promise): include stack trace in an unhandlerd promise

lib/zone.ts

@@ -867,7 +867,7 @@ const Zone: ZoneType = (function(global: any) {
       if (this.data && typeof this.data.handleId !== 'undefined') {
         return this.data.handleId;
       } else {
-        return this.toString();
+        return Object.prototype.toString.call(this);
       }
     }
   }
@@ -994,7 +994,7 @@ const Zone: ZoneType = (function(global: any) {
         if (queue.length == 0 && state == REJECTED) {
           promise[symbolState] = REJECTED_NO_CATCH;
           try {
-            throw new Error("Uncaught (in promise): " +  value);
+            throw new Error("Uncaught (in promise): " +  value + (value && value.stack ? '\n' + value.stack : ''));
           } catch (e) {
             const error: UncaughtPromiseError = e;
             error.rejection = value;

test/common/Promise.spec.ts

@@ -233,6 +233,7 @@ describe('Promise', ifEnvSupports('Promise', function () {
         var promiseError: Error = null;
         var zone: Zone = null;
         var task: Task = null;
+        var error: Error = null;
         queueZone.fork({
           name: 'promise-error',
           onHandleError: (delegate: ZoneDelegate, current: Zone, target: Zone,
@@ -244,13 +245,19 @@ describe('Promise', ifEnvSupports('Promise', function () {
         }).run(() => {
           zone = Zone.current;
           task = Zone.currentTask;
-          Promise.reject('rejectedErrorShouldBeHandled');
+          error = new Error('rejectedErrorShouldBeHandled');
+          try {
+            // throw so that the stack trace is captured
+            throw error;
+          } catch (e) {}
+          Promise.reject(error);
           expect(promiseError).toBe(null);
         });
         setTimeout(() => null);
         setTimeout(() => {
-          expect(promiseError.message).toBe('Uncaught (in promise): rejectedErrorShouldBeHandled');
-          expect(promiseError['rejection']).toBe('rejectedErrorShouldBeHandled');
+          expect(promiseError.message).toBe('Uncaught (in promise): ' + error +
+              (error.stack ? '\n' + error.stack : ''));
+          expect(promiseError['rejection']).toBe(error);
           expect(promiseError['zone']).toBe(zone);
           expect(promiseError['task']).toBe(task);
           done();

test/zone-spec/fake-async-test.spec.ts

@@ -59,7 +59,7 @@ describe('FakeAsyncTestZoneSpec', () => {
         fakeAsyncTestZone.run(() => {
           Promise.resolve(null).then((_) => { throw new Error('async'); });
           expect(() => { testZoneSpec.flushMicrotasks(); })
-            .toThrowError('Uncaught (in promise): Error: async');
+            .toThrowError(/Uncaught \(in promise\): Error: async/);
         });
       });