testing: Fix typo on Logf doc comment.
R=rsc, r2
CC=golang-dev
https://golang.org/cl/4167064
diff --git a/src/pkg/testing/testing.go b/src/pkg/testing/testing.go
index 977252b..cc31451 100644
--- a/src/pkg/testing/testing.go
+++ b/src/pkg/testing/testing.go
@@ -92,7 +92,7 @@
// and records the text in the error log.
func (t *T) Log(args ...interface{}) { t.errors += "\t" + tabify(fmt.Sprintln(args...)) }
-// Log formats its arguments according to the format, analogous to Printf(),
+// Logf formats its arguments according to the format, analogous to Printf(),
// and records the text in the error log.
func (t *T) Logf(format string, args ...interface{}) {
t.errors += "\t" + tabify(fmt.Sprintf(format, args...))
