crypto: reuse X509 issuer result

Avoid a second native call when reading the issuer certificate.

Signed-off-by: Filip Skokan <panva.ip@gmail.com>

Author: panva

lib/internal/crypto/x509.js

@@ -193,7 +193,7 @@ class X509Certificate {
     if (value === undefined) {
       const cert = this[kHandle].getIssuerCert();
       if (cert)
-        value = new InternalX509Certificate(this[kHandle].getIssuerCert());
+        value = new InternalX509Certificate(cert);
       this[kInternalState].set('issuerCertificate', value);
     }
     return value;