Declare nullable strong borrowed ref type for RawServoDeclarationBlock.

components/style/binding_tools/regen.py

@@ -319,6 +319,7 @@ COMPILATION_TARGETS = {
             "RawGeckoNode",
             "RawGeckoElement",
             "RawGeckoDocument",
+            "RawServoDeclarationBlockStrong",
         ],
         "whitelist_functions": [
             "Servo_.*",

components/style/gecko_bindings/bindings.rs

@@ -21,6 +21,8 @@ pub type RawGeckoElementBorrowed<'a> = &'a RawGeckoElement;
 pub type RawGeckoElementBorrowedOrNull<'a> = Option<&'a RawGeckoElement>;
 pub type RawGeckoDocumentBorrowed<'a> = &'a RawGeckoDocument;
 pub type RawGeckoDocumentBorrowedOrNull<'a> = Option<&'a RawGeckoDocument>;
+pub type RawServoDeclarationBlockStrongBorrowed<'a> = &'a RawServoDeclarationBlockStrong;
+pub type RawServoDeclarationBlockStrongBorrowedOrNull<'a> = Option<&'a RawServoDeclarationBlockStrong>;
 pub type RawServoStyleSetBorrowed<'a> = &'a RawServoStyleSet;
 pub type RawServoStyleSetBorrowedMut<'a> = &'a mut RawServoStyleSet;
 pub type RawServoStyleSetOwned = ::gecko_bindings::sugar::ownership::Owned<RawServoStyleSet>;

components/style/gecko_bindings/sugar/ownership.rs

@@ -161,6 +161,20 @@ impl<T> Strong<T> {
         }
     }
 
+    #[inline]
+    /// Given a reference to a strong FFI reference,
+    /// converts it to a reference to a servo-side Arc
+    /// Returns None on null.
+    ///
+    /// Strong<GeckoType> -> Arc<ServoType>
+    pub fn as_arc_opt<U>(&self) -> Option<&Arc<U>> where U: HasArcFFI<FFIType = T> {
+        if self.is_null() {
+            None
+        } else {
+            unsafe { Some(transmute(self)) }
+        }
+    }
+
     #[inline]
     /// Produces a null strong FFI reference
     pub fn null() -> Self {