url: verify domain is not empty after "ToASCII"

Port of whatwg/url#497

PR-URL: #33770
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Shingo Inoue <leko.noor@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

src/node_url.cc

@@ -779,6 +779,8 @@ bool ToASCII(const std::string& input, std::string* output) {
   MaybeStackBuffer<char> buf;
   if (i18n::ToASCII(&buf, input.c_str(), input.length()) < 0)
     return false;
+  if (buf.length() == 0)
+    return false;
   output->assign(*buf, buf.length());
   return true;
 }