Increase timeouts because some CI systems are REALLY SLOW. (#20396)

dev/automated_tests/test_smoke_test/timeout_pass_test.dart

@@ -7,7 +7,7 @@ import 'package:flutter_test/flutter_test.dart';
 void main() {
   testWidgets('flutter_test timeout logic - addTime - positive', (WidgetTester tester) async {
     await tester.runAsync(() async {
-      await new Future<void>.delayed(const Duration(milliseconds: 3500));
-    }, additionalTime: const Duration(milliseconds: 2000));
+      await new Future<void>.delayed(const Duration(milliseconds: 2500)); // must be longer than default timeout.
+    }, additionalTime: const Duration(milliseconds: 2000)); // default timeout is 2s, so this makes it 4s.
   });
 }

packages/flutter_test/lib/src/binding.dart

@@ -695,7 +695,7 @@ class AutomatedTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
         _currentFakeAsync.elapse(duration);
       _phase = newPhase;
       if (hasScheduledFrame) {
-        addTime(const Duration(milliseconds: 100));
+        addTime(const Duration(milliseconds: 500));
         _currentFakeAsync.flushMicrotasks();
         handleBeginFrame(new Duration(
           milliseconds: _clock.now().millisecondsSinceEpoch,
@@ -710,7 +710,7 @@ class AutomatedTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
 
   @override
   Future<T> runAsync<T>(Future<T> callback(), {
-    Duration additionalTime = const Duration(milliseconds: 250),
+    Duration additionalTime = const Duration(milliseconds: 1000),
   }) {
     assert(additionalTime != null);
     assert(() {