De-flake the bad-server-subframe test.

Delay navigating an iframe until after the main frame has finished
loading its document so that, in case the iframe is in another process
due to site isolation, the logging from the main frame and the iframe
do not race and create flaky results.

R=dgozman@chromium.org

Bug: 1088441
Change-Id: Id33996ac3a07c307fde2b0fc099e35f1e2f0500f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2229402
Commit-Queue: danakj <danakj@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#775242}

third_party/blink/web_tests/TestExpectations

@@ -5954,7 +5954,6 @@ crbug.com/1007228 [ Mac ] external/wpt/fullscreen/api/element-request-fullscreen
 crbug.com/1011811 http/tests/devtools/persistence/automapping-sourcemap.js [ Pass Failure ]
 
 # Sheriff 2020-06-03
-crbug.com/1088441 [ Mac ] http/tests/loading/bad-server-subframe.html [ Pass Failure ]
 crbug.com/1090822 [ Mac10.10 ] virtual/cascade/fast/forms/month/month-appearance-basic.html [ Pass Failure ]
 crbug.com/1083293 [ Linux ] media/video-aspect-ratio.html [ Pass Failure ]
 

third_party/blink/web_tests/http/tests/loading/bad-scheme-subframe.html

@@ -3,6 +3,9 @@ if (window.testRunner)
     testRunner.dumpAsText();
 
 window.onload = function() {
+  // Navigate the iframe from onload, so that it happens after all loading
+  // logs from the main frame are complete. This avoids log ordering races
+  // if the iframe is loaded in another process due to site isolation.
   var i = document.createElement("iframe");
   i.name = "f1";
   i.src = "this-is-definitely-a-bad-uri-scheme:";

third_party/blink/web_tests/http/tests/loading/bad-server-subframe-expected.txt

 main frame - DidStartNavigation
 main frame - ReadyToCommitNavigation
 main frame - didCommitLoadForFrame
+main frame - didFinishDocumentLoadForFrame
 frame "f1" - BeginNavigation request to 'http://localhost:54321/', http method GET
 frame "f1" - DidStartNavigation
-main frame - didFinishDocumentLoadForFrame
+main frame - didHandleOnloadEventsForFrame
 frame "f1" - didFailProvisionalLoadWithError
 frame "f1" - DidStartNavigation
 frame "f1" - ReadyToCommitNavigation
@@ -11,7 +12,6 @@ frame "f1" - didCommitLoadForFrame
 frame "f1" - didFinishDocumentLoadForFrame
 frame "f1" - didHandleOnloadEventsForFrame
 frame "f1" - didFinishLoadForFrame
-main frame - didHandleOnloadEventsForFrame
 main frame - didFinishLoadForFrame
 This is a test of load callbacks. It is only useful inside the regression test tool.
 It also assumes there is no web server running locally on port 54321.

third_party/blink/web_tests/http/tests/loading/bad-server-subframe.html

 <script>
 if (window.testRunner)
     testRunner.dumpAsText();
+
+window.onload = function() {
+  // Navigate the iframe from onload, so that it happens after all loading
+  // logs from the main frame are complete. This avoids log ordering races
+  // if the iframe is loaded in another process due to site isolation.
+  var i = document.createElement("iframe");
+  i.name = "f1";
+  i.src = "http://localhost:54321";
+  document.body.appendChild(i);
+}
 </script>
 This is a test of load callbacks. It is only useful inside the regression test tool.<br>
 It also assumes there is no web server running locally on port 54321.<br>
-<iframe name="f1" src="http://localhost:54321"></iframe>