LibWeb: Add XMLHttpRequest::timeout setter and getter

Userland/Libraries/LibWeb/XHR/XMLHttpRequest.cpp

@@ -693,4 +693,23 @@ DOM::ExceptionOr<void> XMLHttpRequest::override_mime_type(String const& mime)
 
     return {};
 }
+
+// https://xhr.spec.whatwg.org/#ref-for-dom-xmlhttprequest-timeout%E2%91%A2
+DOM::ExceptionOr<void> XMLHttpRequest::set_timeout(u32 timeout)
+{
+    // 1. If the current global object is a Window object and this’s synchronous flag is set,
+    //    then throw an "InvalidAccessError" DOMException.
+    auto& global_object = wrapper()->global_object();
+    if (global_object.class_name() == "WindowObject" && m_synchronous)
+        return DOM::InvalidAccessError::create("Use of XMLHttpRequest's timeout attribute is not supported in the synchronous mode in window context.");
+
+    // 2. Set this’s timeout to the given value.
+    m_timeout = timeout;
+
+    return {};
+}
+
+// https://xhr.spec.whatwg.org/#dom-xmlhttprequest-timeout
+u32 XMLHttpRequest::timeout() const { return m_timeout; }
+
 }

Userland/Libraries/LibWeb/XHR/XMLHttpRequest.h

@@ -71,6 +71,9 @@ public:
 
     DOM::ExceptionOr<void> override_mime_type(String const& mime);
 
+    DOM::ExceptionOr<void> set_timeout(u32 timeout);
+    u32 timeout() const;
+
 private:
     virtual void ref_event_target() override { ref(); }
     virtual void unref_event_target() override { unref(); }
@@ -96,6 +99,7 @@ private:
     ReadyState m_ready_state { ReadyState::Unsent };
     unsigned m_status { 0 };
     bool m_send { false };
+    u32 m_timeout { 0 };
 
     String m_method;
     AK::URL m_url;

Userland/Libraries/LibWeb/XHR/XMLHttpRequest.idl

@@ -25,6 +25,7 @@ interface XMLHttpRequest : XMLHttpRequestEventTarget {
     readonly attribute DOMString responseText;
     readonly attribute any response;
     attribute XMLHttpRequestResponseType responseType;
+    attribute unsigned long timeout;
 
     undefined open(DOMString method, DOMString url);
     undefined open(ByteString method, USVString url, boolean async, optional USVString? username = {}, optional USVString? password = {});