go/types/internal/play: show AST debug representation too

Change-Id: Id3109a9dd058c08156b120471f59df34703aeecb
Reviewed-on: https://go-review.googlesource.com/c/tools/+/479975
Run-TryBot: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
diff --git a/go/types/internal/play/play.go b/go/types/internal/play/play.go
index 8be804b4..e53d988 100644
--- a/go/types/internal/play/play.go
+++ b/go/types/internal/play/play.go
@@ -165,6 +165,9 @@
 	}
 	fmt.Fprintf(out, "\n")
 
+	// Syntax debug output.
+	ast.Fprint(out, fset, path[0], nil) // ignore errors
+
 	// Clean up the messy temp file name.
 	outStr := strings.ReplaceAll(out.String(), f.Name(), "play.go")