diff --git a/components/style/gecko/wrapper.rs b/components/style/gecko/wrapper.rs
index bcdd2755519..c8fc86a5063 100644
--- a/components/style/gecko/wrapper.rs
+++ b/components/style/gecko/wrapper.rs
@@ -148,6 +148,12 @@ impl<'ln> GeckoNode<'ln> {
         (self.0).mBoolFlags
     }
 
+    /// Owner document quirks mode getter.
+    #[inline]
+    pub fn owner_document_quirks_mode(&self) -> QuirksMode {
+        self.owner_doc().mCompatMode.into()
+    }
+
     #[inline]
     fn get_bool_flag(&self, flag: nsINode_BooleanFlag) -> bool {
         self.bool_flags() & (1u32 << flag as u32) != 0
@@ -625,8 +631,9 @@ impl<'le> GeckoElement<'le> {
     }
 
     /// Owner document quirks mode getter.
+    #[inline]
     pub fn owner_document_quirks_mode(&self) -> QuirksMode {
-        self.as_node().owner_doc().mCompatMode.into()
+        self.as_node().owner_document_quirks_mode()
     }
 
     /// Only safe to call on the main thread, with exclusive access to the element and
diff --git a/ports/geckolib/glue.rs b/ports/geckolib/glue.rs
index e5a21612dfb..b793c7d24e5 100644
--- a/ports/geckolib/glue.rs
+++ b/ports/geckolib/glue.rs
@@ -29,9 +29,9 @@ use style::gecko::global_style_data::{GLOBAL_STYLE_DATA, GlobalStyleData, STYLE_
 use style::gecko::restyle_damage::GeckoRestyleDamage;
 use style::gecko::selector_parser::PseudoElement;
 use style::gecko::traversal::RecalcStyleOnly;
-use style::gecko::wrapper::GeckoElement;
+use style::gecko::wrapper::{GeckoElement, GeckoNode};
 use style::gecko_bindings::bindings;
-use style::gecko_bindings::bindings::{RawGeckoElementBorrowed, RawGeckoElementBorrowedOrNull};
+use style::gecko_bindings::bindings::{RawGeckoElementBorrowed, RawGeckoElementBorrowedOrNull, RawGeckoNodeBorrowed};
 use style::gecko_bindings::bindings::{RawGeckoKeyframeListBorrowed, RawGeckoKeyframeListBorrowedMut};
 use style::gecko_bindings::bindings::{RawServoDeclarationBlockBorrowed, RawServoDeclarationBlockStrong};
 use style::gecko_bindings::bindings::{RawServoDocumentRule, RawServoDocumentRuleBorrowed};
@@ -1614,6 +1614,29 @@ pub unsafe extern "C" fn Servo_SelectorList_Matches(
     )
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn Servo_SelectorList_QueryFirst(
+    node: RawGeckoNodeBorrowed,
+    selectors: RawServoSelectorListBorrowed,
+) -> *const structs::RawGeckoElement {
+    use std::borrow::Borrow;
+    use style::dom_apis::{self, QuerySelectorResult, QuerySelectorKind};
+
+    let node = GeckoNode(node);
+    let selectors = ::selectors::SelectorList::from_ffi(selectors).borrow();
+    let mut result = QuerySelectorResult::new();
+    dom_apis::query_selector::<GeckoElement>(
+        node,
+        &selectors,
+        &mut result,
+        QuerySelectorKind::First,
+        node.owner_document_quirks_mode(),
+    );
+
+    result.first()
+        .map_or(ptr::null(), |e| e.0)
+}
+
 #[no_mangle]
 pub extern "C" fn Servo_ImportRule_GetHref(rule: RawServoImportRuleBorrowed, result: *mut nsAString) {
     read_locked_arc(rule, |rule: &ImportRule| {