test: add some tests where go/defer arg starts with parenthesis

R=gri
CC=golang-dev
https://golang.org/cl/6890047

test/fixedbugs/issue4468.go

@@ -8,7 +8,21 @@
 
 package p
 
+type T int
+
+func (t *T) F() T {
+	return *t
+}
+
+type S struct {
+	t T
+}
+
 func F() {
 	go (F())	// ERROR "must be function call"
 	defer (F())	// ERROR "must be function call"
+	var s S
+	(&s.t).F()
+	go (&s.t).F()
+	defer (&s.t).F()
 }