Auto merge of #15354 - cynicaldevil:manual-redirect, r=jdm

Redirect document loads manually

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---
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #14596 .

r? @jdm

I ran some tests at random from the `navigating-across-documents` folder, and they are passing.

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tests/wpt/mozilla/meta/MANIFEST.json

@@ -13352,6 +13352,12 @@
      {}
     ]
    ],
+   "mozilla/multiple_redirects.html": [
+    [
+     "/_mozilla/mozilla/multiple_redirects.html",
+     {}
+    ]
+   ],
    "mozilla/navigator.html": [
     [
      "/_mozilla/mozilla/navigator.html",
@@ -26021,6 +26027,10 @@
    "f8f9adebe09f9473a52e5ec4f075540b10b32d7e",
    "testharness"
   ],
+  "mozilla/multiple_redirects.html": [
+   "db0ffd3db5b23204b91f332915d938cfc85ec46c",
+   "testharness"
+  ],
   "mozilla/navigator.html": [
    "939f453fecfb28a36cb93057382b56439b00b136",
    "testharness"