io/ioutil: add WriteString to Discard

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/12580045

diff --git a/src/pkg/io/ioutil/ioutil.go b/src/pkg/io/ioutil/ioutil.go
index ce8d8b48acab72c6652d60bf4d63dbe935507b98..b2508b7899ea6d39e05f23ad6c756000f50778e8 100644 (file)
--- a/src/pkg/io/ioutil/ioutil.go
+++ b/src/pkg/io/ioutil/ioutil.go
@@ -132,6 +132,10 @@ func (devNull) Write(p []byte) (int, error) {
        return len(p), nil
 }
 
+func (devNull) WriteString(s string) (int, error) {
+       return len(s), nil
+}
+
 func (devNull) ReadFrom(r io.Reader) (n int64, err error) {
        buf := blackHole()
        defer blackHolePut(buf)