Increase the timeout for a failing pub test.

sdk/lib/_internal/pub/test/serve/utils.dart

Index: sdk/lib/_internal/pub/test/serve/utils.dart
diff --git a/sdk/lib/_internal/pub/test/serve/utils.dart b/sdk/lib/_internal/pub/test/serve/utils.dart
index 43f1966f27d901fc1cf08a4780ad298649b59d63..039480307b309910d7877d216129c87859b8c2b6 100644
--- a/sdk/lib/_internal/pub/test/serve/utils.dart
+++ b/sdk/lib/_internal/pub/test/serve/utils.dart
@@ -106,7 +106,7 @@ ScheduledProcess startPubServe([Iterable<String> args]) {
 
   // Dart2js can take a long time to compile dart code, so we increase the
   // timeout to cope with that.
-  currentSchedule.timeout = new Duration(seconds: 15);
+  currentSchedule.timeout *= 1.5;
 
   return startPub(args: pubArgs);
 }