Auto merge of #20780 - gterzian:fix_beforeunload_test, r=cbrewster

update "navigation within beforeunload" test to match the spec

<!-- Please describe your changes on the following line: -->
 Follow up on https://github.com/servo/servo/pull/20329#issuecomment-387138449
@cbrewster

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- [ ] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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components/script/dom/window.rs

@@ -1560,7 +1560,7 @@ impl Window {
 
         let pipeline_id = self.upcast::<GlobalScope>().pipeline_id();
 
-        // Step 4
+        // Step 4 and 5
         let window_proxy = self.window_proxy();
         if let Some(active) = window_proxy.currently_active() {
             if pipeline_id == active {

tests/wpt/metadata/MANIFEST.json

@@ -564742,7 +564742,7 @@
    "support"
   ],
   "html/browsers/browsing-the-web/unloading-documents/navigation-within-beforeunload.html": [
-   "8e48ede5ef227e88a091f1d33b385d0b3dff713c",
+   "49a3e27670f5902309f45be654ad9e12d7f9c500",
    "testharness"
   ],
   "html/browsers/browsing-the-web/unloading-documents/pagehide-on-history-forward-1.html": [

tests/wpt/metadata/html/browsers/browsing-the-web/unloading-documents/navigation-within-beforeunload.html.ini

@@ -1,5 +0,0 @@
-[navigation-within-beforeunload.html]
-  type: testharness
-  [Triggering navigation from within beforeunload event]
-    expected: FAIL
-

tests/wpt/web-platform-tests/html/browsers/browsing-the-web/unloading-documents/navigation-within-beforeunload.html

@@ -15,7 +15,10 @@ onload = function() {setTimeout(function() {
 
   iframe.onload = function() {
                     setTimeout(function() {iframe.contentWindow.location="navigation-within-beforeunload-2.html";}, 100);
-                    iframe.onload = t.step_func(function() {assert_equals(counter, 1000); t.done()});
+                    // Step 4 of https://html.spec.whatwg.org/multipage/browsing-the-web.html#navigating-across-documents
+                    // doesn't seem to allow navigation within a beforeunload handler,
+                    // so the counter should not go beyond 1.
+                    iframe.onload = t.step_func(function() {assert_equals(counter, 1); t.done()});
                   };
 
   iframe.src = "navigation-within-beforeunload-1.html?" + Math.random();