Make step 3 of XHR's SetResponseType method match the specification

components/script/dom/xmlhttprequest.rs

@@ -675,19 +675,21 @@ impl XMLHttpRequestMethods for XMLHttpRequest {
     // https://xhr.spec.whatwg.org/#the-responsetype-attribute
     fn SetResponseType(&self, response_type: XMLHttpRequestResponseType) -> ErrorResult {
         match self.global() {
-            GlobalRoot::Worker(_) if response_type == XMLHttpRequestResponseType::Document
+            GlobalRoot::Worker(_) if response_type == XMLHttpRequestResponseType::Document => return Ok(()),
-            => return Ok(()),
             _ => {}
         }
         match self.ready_state.get() {
             XMLHttpRequestState::Loading | XMLHttpRequestState::Done => Err(Error::InvalidState),
-            _ if self.sync.get() => Err(Error::InvalidAccess),
             _ => {
+                if let (GlobalRoot::Window(_), true) = (self.global(), self.sync.get()) {
+                    Err(Error::InvalidAccess)
+                } else {
                     self.response_type.set(response_type);
                     Ok(())
                 }
             }
         }
+    }
 
     #[allow(unsafe_code)]
     // https://xhr.spec.whatwg.org/#the-response-attribute