gc: add ... T, rework plain ...

No longer a distinct type; now a property of func types.

R=ken2
CC=golang-dev
https://golang.org/cl/197042
diff --git a/test/ddd2.go b/test/ddd2.go
new file mode 100644
index 0000000..a06af0c
--- /dev/null
+++ b/test/ddd2.go
@@ -0,0 +1,16 @@
+// true
+
+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ddd
+
+func Sum(args ...int) int {
+	s := 0
+	for _, v := range args {
+		s += v
+	}
+	return s
+}
+