servo: Merge #18009 - stylo: Fix skip_root_and_item_display_fixup (from emilio:video-controls); r=heycam

The check isn't doing what the comment is saying.

XBL subtrees for video controls all have the
NODE_IS_IN_NATIVE_ANONYMOUS_SUBTREE flag, but not all of them are NAC
themselves, so we may incorrectly miss blockification.

Bug: 1366163
Reviewed-by: heycam
MozReview-Commit-ID: Oq3W258Lz2
Source-Repo: https://github.com/servo/servo
Source-Revision: 5ecedb562c66c1f436850704b6dc467a04f5a283

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : 4ac2d18a9f0b660d8bc869a436d6e2e210d07302

servo/components/style/gecko/wrapper.rs

@@ -238,7 +238,6 @@ impl<'ln> GeckoNode<'ln> {
     /// This logic is duplicated in Gecko's nsIContent::IsInAnonymousSubtree.
     #[inline]
     fn is_in_anonymous_subtree(&self) -> bool {
-        use gecko_bindings::structs::NODE_IS_IN_NATIVE_ANONYMOUS_SUBTREE;
         use gecko_bindings::structs::NODE_IS_IN_SHADOW_TREE;
         self.flags() & (NODE_IS_IN_NATIVE_ANONYMOUS_SUBTREE as u32) != 0 ||
         ((self.flags() & (NODE_IS_IN_SHADOW_TREE as u32) == 0) &&
@@ -1144,7 +1143,7 @@ impl<'le> TElement for GeckoElement<'le> {
         // level native anonymous content subtree roots, since they're not
         // really roots from the style fixup perspective.  Checking that we
         // are NAC handles both cases.
-        self.flags() & (NODE_IS_IN_NATIVE_ANONYMOUS_SUBTREE as u32) != 0
+        self.is_native_anonymous()
     }
 
     unsafe fn set_selector_flags(&self, flags: ElementSelectorFlags) {