[webcrypto] Fix a leak in RSA private key import using JWK.

BUG=375808,245025,373542
TBR=rsleevi

Review URL: https://codereview.chromium.org/299623007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@271920 0039d316-1c4b-4281-b951-d872f2087c98

content/child/webcrypto/platform_crypto_nss.cc

@@ -1609,6 +1609,9 @@ Status ImportRsaPrivateKey(const blink::WebCryptoAlgorithm& algorithm,
 
   crypto::ScopedSECKEYPrivateKey private_key(
       PK11_FindKeyByKeyID(slot.get(), &object_id, NULL));
+
+  SECITEM_FreeItem(&object_id, PR_FALSE);
+
   if (!private_key)
     return Status::OperationError();