Restore hidden-elements.html test to original form

As pointed out in this thread [1], <source> and <track> don't have
explicitly specified display properties, so they should default to
display: inline. This CL restores the test that looks for 'inline'.

[1] https://github.com/web-platform-tests/wpt/pull/29883#issuecomment-894124180

Bug: 1231263
Change-Id: I03937953228b0e83625d3a51a3a9ff71f6230827
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3082495
Commit-Queue: Mason Freed <masonf@chromium.org>
Commit-Queue: Joey Arhar <jarhar@chromium.org>
Auto-Submit: Mason Freed <masonf@chromium.org>
Reviewed-by: Joey Arhar <jarhar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#910046}
diff --git a/html/rendering/non-replaced-elements/hidden-elements.html b/html/rendering/non-replaced-elements/hidden-elements.html
index 577f32d..4286681 100644
--- a/html/rendering/non-replaced-elements/hidden-elements.html
+++ b/html/rendering/non-replaced-elements/hidden-elements.html
@@ -13,27 +13,23 @@
   "noframes", "param", "rp", "script", "style", "template", "title",
 ];
 
-function isDisplayNone(element) {
-  return getComputedStyle(element).display === "none";
-}
-
 for (let name of kNotHiddenElementLocalNames) {
   test(function() {
     let element = document.createElement(name);
     document.body.appendChild(element);
-    assert_false(isDisplayNone(element));
-  }, `${name} should not be display:none`);
+    assert_equals(getComputedStyle(element).display, "inline");
+  }, `${name} should not be hidden`);
 }
 
 for (let name of kHiddenElementLocalNames) {
   test(function() {
     let element = document.createElement(name);
     document.body.appendChild(element);
-    assert_true(isDisplayNone(element));
-  }, `${name} should be display:none`);
+    assert_equals(getComputedStyle(element).display, "none");
+  }, `${name} should be hidden`);
 }
 
 test(function() {
-  assert_true(isDisplayNone(document.querySelector("[hidden]")));
-}, `[hidden] element should be display:none`);
+  assert_equals(getComputedStyle(document.querySelector("[hidden]")).display, "none");
+}, `[hidden] element should be hidden`);
 </script>