LibWeb: Use DOMException in XMLHttpRequest::send()

Author: https://github.com/linusg
Commit: 14058b6858
Pull-request: https://github.com/SerenityOS/serenity/pull/5417

Userland/Libraries/LibWeb/XHR/XMLHttpRequest.h

@@ -71,7 +71,7 @@ public:
     String response_text() const;
 
     DOM::ExceptionOr<void> open(const String& method, const String& url);
-    void send();
+    DOM::ExceptionOr<void> send();
 
     DOM::ExceptionOr<void> set_request_header(const String& header, const String& value);