internal/ethapi: make resent gas params optional

internal/ethapi/api.go

@@ -1337,10 +1337,10 @@ func (s *PublicTransactionPoolAPI) Resend(ctx context.Context, sendArgs SendTxAr
 
 		if pFrom, err := types.Sender(signer, p); err == nil && pFrom == sendArgs.From && signer.Hash(p) == wantSigHash {
 			// Match. Re-sign and send the transaction.
-			if gasPrice != nil {
+			if gasPrice != nil && (*big.Int)(gasPrice).Sign() != 0 {
 				sendArgs.GasPrice = gasPrice
 			}
-			if gasLimit != nil {
+			if gasLimit != nil && *gasLimit != 0 {
 				sendArgs.Gas = gasLimit
 			}
 			signedTx, err := s.sign(sendArgs.From, sendArgs.toTransaction())