Make two promise-related tests deterministic

third_party/WebKit/LayoutTests/external/wpt/html/webappapis/scripting/processing-model-2/unhandled-promise-rejections/promise-rejection-events-onerror.html

Index: third_party/WebKit/LayoutTests/external/wpt/html/webappapis/scripting/processing-model-2/unhandled-promise-rejections/promise-rejection-events-onerror.html
diff --git a/third_party/WebKit/LayoutTests/external/wpt/html/webappapis/scripting/processing-model-2/unhandled-promise-rejections/promise-rejection-events-onerror.html b/third_party/WebKit/LayoutTests/external/wpt/html/webappapis/scripting/processing-model-2/unhandled-promise-rejections/promise-rejection-events-onerror.html
index 386af169a641da503f2b860c9ef32db56bc518f2..c76d531c43ec3ecc8cbf3c21f3a0ffa4db7be715 100644
--- a/third_party/WebKit/LayoutTests/external/wpt/html/webappapis/scripting/processing-model-2/unhandled-promise-rejections/promise-rejection-events-onerror.html
+++ b/third_party/WebKit/LayoutTests/external/wpt/html/webappapis/scripting/processing-model-2/unhandled-promise-rejections/promise-rejection-events-onerror.html
@@ -27,9 +27,11 @@ async_test(function(t) {
   };
 
   var p = Promise.reject(e);
-  setTimeout(t.step_func(function() {
-    // This will cause onrejectionhandled
-    p.catch(function() {});
-  }), 1);
+  setTimeout(function() {
+    setTimeout(t.step_func(function() {
+      // This will cause onrejectionhandled
+      p.catch(function() {});
+    }), 0);
+  }, 0);
 }, 'Throwing inside an unhandledrejection handler invokes the error handler.');
 </script>