playground: hit golang.org/compile endpoint instead of play.golang.org

Not sure why this was originally going via the playground. It needn't.

Change-Id: I40b5886a56ba4b941ff74f4bc325625412d7eaff
Reviewed-on: https://go-review.googlesource.com/22497
Reviewed-by: Andrew Gerrand <adg@golang.org>
diff --git a/playground/common.go b/playground/common.go
index d8c2805..2d11d5d 100644
--- a/playground/common.go
+++ b/playground/common.go
@@ -15,7 +15,7 @@
 	"net/http"
 )
 
-const baseURL = "http://play.golang.org"
+const baseURL = "https://golang.org/compile?output=json"
 
 func init() {
 	http.HandleFunc("/compile", bounce)