gc: issue 1231

Fixes #1231.

R=ken2
CC=golang-dev
https://golang.org/cl/3627041
diff --git a/test/closure.go b/test/closure.go
index 54e4cf8..3033c02 100644
--- a/test/closure.go
+++ b/test/closure.go
@@ -98,4 +98,15 @@
 		println("newfunc returned broken funcs")
 		panic("fail")
 	}
+
+	ff(1)
+}
+
+func ff(x int) {
+	call(func() {
+		_ = x
+	})
+}
+
+func call(func()) {
 }