Update test expectations for Element.focus change.

Element.focus() now centers an element in the block and inline
directions when the element should be scrolled into view. Update tests
to account for this.

Differential Revision: https://phabricator.services.mozilla.com/D183541

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1842679
gecko-commit: 7ffbd7298f7b4d38aad4c5af4e08a00e626d2c09
gecko-reviewers: emilio, credential-management-reviewers, devtools-reviewers, sgalich, ochameau

css/css-scroll-snap/scroll-target-margin-005.html

@@ -23,12 +23,14 @@
 
 <script>
 promise_test(async function() {
-   document.scrollingElement.scrollTo(0, 20000);
-   await new Promise(resolve => {
-     document.addEventListener("scroll", resolve, { once: true });
-     document.getElementById("target").focus();
-   });
-  // Should be around 4900 (5000 - 200px of margin). Give some leeway to account for line height / borders / input padding / etc.
-  assert_between_exclusive(document.scrollingElement.scrollTop, 4600, 4850, "Should honor date input scroll-margin");
+  document.scrollingElement.scrollTo(0, 20000);
+  await new Promise(resolve => {
+    document.addEventListener("scroll", resolve, { once: true });
+    document.getElementById("target").focus();
+  });
+  // Should be around 5000 - 200px of margin - (window.innerHeight / 2)
+  const targetPos = 4900 - (window.innerHeight / 2);
+  assert_between_exclusive(document.scrollingElement.scrollTop, targetPos - 300,
+                           targetPos + 300, "Should honor date input scroll-margin");
 });
 </script>