(TBR) update test to run with new task model

pkg/analysis_server/test/services/completion/completion_computer_test.dart

Index: pkg/analysis_server/test/services/completion/completion_computer_test.dart
diff --git a/pkg/analysis_server/test/services/completion/completion_computer_test.dart b/pkg/analysis_server/test/services/completion/completion_computer_test.dart
index 48f9fe6b2c51ee28527817546c308e5b9d7c117b..21b33932ac6b8e86477987b2fbcf073b69642709 100644
--- a/pkg/analysis_server/test/services/completion/completion_computer_test.dart
+++ b/pkg/analysis_server/test/services/completion/completion_computer_test.dart
@@ -113,7 +113,7 @@ class DartCompletionManagerTest extends AbstractSingleUnitTest {
       // There is only one notification
       expect(count, equals(1));
     });
-    return pumpEventQueue().then((_) {
+    return pumpEventQueue(150).then((_) {
       expect(done, isTrue);
     });
   }