feat(core): provide an error context when an exception happens in an error handler

modules/angular2/src/test_lib/fake_async.dart

@@ -80,6 +80,13 @@ void tick([int millis = 0]) {
   _fakeAsync.elapse(duration);
 }
 
+/**
+ * This is not needed in Dart. Because quiver correctly removes a timer when
+ * it throws an exception.
+ */
+void clearPendingTimers() {
+}
+
 /**
  * Flush any pending microtasks.
  */

modules/angular2/src/test_lib/fake_async.ts

@@ -41,9 +41,7 @@ export function fakeAsync(fn: Function): Function {
   return function(...args) {
     // TODO(tbosch): This class should already be part of the jasmine typings but it is not...
     _scheduler = new (<any>jasmine).DelayedFunctionScheduler();
-    ListWrapper.clear(_microtasks);
-    ListWrapper.clear(_pendingPeriodicTimers);
-    ListWrapper.clear(_pendingTimers);
+    clearPendingTimers();
 
     let res = fakeAsyncZone.run(() => {
       let res = fn(...args);
@@ -67,6 +65,14 @@ export function fakeAsync(fn: Function): Function {
   }
 }
 
+// TODO we should fix tick to dequeue the failed timer instead of relying on clearPendingTimers
+export function clearPendingTimers() {
+  ListWrapper.clear(_microtasks);
+  ListWrapper.clear(_pendingPeriodicTimers);
+  ListWrapper.clear(_pendingTimers);
+}
+
+
 /**
  * Simulates the asynchronous passage of time for the timers in the fakeAsync zone.
  *

modules/angular2/src/test_lib/test_lib.ts

@@ -32,6 +32,7 @@ export interface NgMatchers extends jasmine.Matchers {
 
 export var expect: (actual: any) => NgMatchers = <any>_global.expect;
 
+// TODO vsavkin: remove it and use lang/isDart instead
 export var IS_DARTIUM = false;
 
 export class AsyncTestCompleter {