test: enable tests using v, ok := <-ch syntax

R=rsc, r
CC=golang-dev
https://golang.org/cl/4290059
diff --git a/test/fixedbugs/bug234.go b/test/fixedbugs/bug234.go
index 9affad0..562109a 100644
--- a/test/fixedbugs/bug234.go
+++ b/test/fixedbugs/bug234.go
@@ -7,17 +7,17 @@
 package main
 
 func main() {
-	//TODO(rsc): uncomment when this syntax is valid for receive+check closed
-	//	c := make(chan int, 1)
-	//	c <- 100
-	//	x, ok := <-c
-	//	if x != 100 || !ok {
-	//		println("x=", x, " ok=", ok, " want 100, true")
-	//		panic("fail")
-	//	}
-	//	x, ok = <-c
-	//	if x != 0 || ok {
-	//		println("x=", x, " ok=", ok, " want 0, false")
-	//		panic("fail")
-	//	}
+	c := make(chan int, 1)
+	c <- 100
+	x, ok := <-c
+	if x != 100 || !ok {
+		println("x=", x, " ok=", ok, " want 100, true")
+		panic("fail")
+	}
+	close(c)
+	x, ok = <-c
+	if x != 0 || ok {
+		println("x=", x, " ok=", ok, " want 0, false")
+		panic("fail")
+	}
 }