Skip TestNewListenerAndURL on NaCl (#201)

* Skip TestNewListenerAndURL on NaCl

* Updated skip message

internal/driver/webui_test.go

 	"net/url"
 	"os/exec"
 	"regexp"
+	"runtime"
 	"testing"
 
 	"github.com/google/pprof/internal/plugin"
 }
 
 func TestNewListenerAndURL(t *testing.T) {
+	if runtime.GOOS == "nacl" {
+		t.Skip("test assumes tcp available")
+	}
+
 	tests := []struct {
 		hostport  string
 		wantErr   bool