Bug 1801798. Fix gfx/tests/crashtests/1685009-1.html so that it doesn't leave windows open after it finishes. r=layout-reviewers,emilio

For some reason this test only leaves windows open in release, esr, beta, or beta simulation builds.

The form submit opens the test file in a new window, which repeats the same thing.

It causes a problem later because the crashtest window is totally covered and the test image/test/crashtests/1629490-1.html tries to do a requestAnimationFrame which doesn't get run because we aren't ticking the covered window.

Differential Revision: https://phabricator.services.mozilla.com/D217562

gfx/tests/crashtests/1685009-1.html

@@ -1,12 +1,16 @@
 <script>
-window.requestIdleCallback(() => {
-  window.close();
-})
-window.onload = () => {
-  a.value = "J."
-  b.submit()
-  window.requestAnimationFrame(() => { a.setRangeText("foo") })
+if (location.search == "?x=") {
+  setTimeout(() => { window.close(); }, 1000);
+} else {
+  window.requestIdleCallback(() => {
+    window.close();
+  })
+  window.onload = () => {
+    a.value = "J."
+    b.submit()
+    window.requestAnimationFrame(() => { a.setRangeText("foo") })
+  }
 }
 </script>
 <textarea id="a" style="max-width: 0"></textarea>
-<form id="b" target="a">
+<form id="b" target="a"><input name="x" type="hidden">