Windows Issue: gopherjs test ... does fail under Windows

Probably related to #341 : 

``` go
//file dummy_test.go:

package dummy

import "testing"

func TestNothing(t *testing.T) {
}
```
### go test ...pathtodummypackage

gives: **ok**
### gopherjs test ......pathtodummypackage

gives: **FAIL**

without any further info.
(Win7, 64/Node 4.2.1+sourcemap).
There are no syscalls involved while testing, right ?
