Add support for skipping display fixup for pseudos.

This is needed for https://bugzilla.mozilla.org/show_bug.cgi?id=1346481

components/style/gecko_bindings/bindings.rs

@@ -1666,6 +1666,7 @@ extern "C" {
     pub fn Servo_ComputedValues_GetForAnonymousBox(parent_style_or_null:
                                                        ServoComputedValuesBorrowedOrNull,
                                                    pseudoTag: *mut nsIAtom,
+                                                   skip_display_fixup: bool,
                                                    set:
                                                        RawServoStyleSetBorrowed)
      -> ServoComputedValuesStrong;