[Webkit-unassigned] [Bug 222590] New: Maybe-regression(STP121): window.open flakily returning null

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=222590

            Bug ID: 222590
           Summary: Maybe-regression(STP121): window.open flakily
                    returning null
           Product: WebKit
           Version: WebKit Nightly Build
          Hardware: Unspecified
                OS: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Frames
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: gsnedders at apple.com

e.g. see: https://wpt.fyi/results/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/creating_browsing_context_test_01.html?q=seq%28status%3Aok%7Cstatus%3Apass%20status%3Aok%7Cstatus%3Apass%20status%3Aok%7Cstatus%3Apass%20status%3A%21ok%26status%3A%21pass%20status%3A%21ok%26status%3A%21pass%20status%3A%21ok%26status%3A%21pass%20%29&run_id=5635506173902848&run_id=5722139221032960&run_id=5714889316237312&run_id=5731985836212224&run_id=5670691686842368&run_id=6262793999220736

That it reproduces 100% of the time on Azure Pipelines but only ~15% of the time locally, which makes me suspect this is some sort of race condition where CI always loses due to relatively low performance.

The code here is pretty simple:

  var currentUrl = 'http://' + window.location.host + '/common/blank.html';
  var win = window.open(currentUrl, '', 'height=1,width=1');
  this.add_cleanup(function() { win.close(); });
  win.onload = this.step_func_done(function () {
    ...

This is throwing when trying to set win.onload as win is null. It shouldn't be, it should be a WindowProxy. (Note that WPT is run with WebKitJavaScriptCanOpenWindowsAutomatically set to 1.)

We also see window.open returning null in html/browsers/windows/browsing-context-names/choose-_blank-001.html, which is even simpler:

  var window1 = window.open('about:blank', '_blank');
  var window2 = window.open('about:blank', '_blank');
  var window3 = window.open('about:blank', '_blank');
  ...

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