_test.inc.js files improperly included when not building tests #655
Description
To reproduce, create a simple package:
main.go:
package main
func main() {}
main_test.go:
package main
import "testing"
func TestFoo(t *testing.T) {}
main_test.inc.js:
/* main_test.inc.js */
then compile:
$ gopherjs build -o main.js
And observe that the output contains the contents of the inc.js file:
$ grep -n main_test main.js
2331: /* main_test.inc.js */