stylo: Fix propagation of quirks mode information to servo side

It was getting inial value from gecko side before and that was always
eCompatibility_NavQuirks. Created an FFI to fetch quirks mode.

components/style/gecko/generated/bindings.rs

@@ -1874,6 +1874,10 @@ extern "C" {
     pub fn Servo_StyleSet_MediumFeaturesChanged(set: RawServoStyleSetBorrowed)
      -> bool;
 }
+extern "C" {
+    pub fn Servo_StyleSet_CompatModeChanged(raw_data:
+                                                RawServoStyleSetBorrowed);
+}
 extern "C" {
     pub fn Servo_StyleSet_AppendStyleSheet(set: RawServoStyleSetBorrowed,
                                            sheet: RawServoStyleSheetBorrowed,