cmd/gogio: join all endtoend tests as subtests

This means we can deduplicate some of the logic, and keep it all in one
place.

Start expanding the logic too; the tests are slow, so they should be
skipped on 'go test -short'. The ones we have so far all run in a matter
of seconds on an average laptop today, but future tests will probably
require heavier work like wine or kvm.

Signed-off-by: Daniel Martí <mvdan@mvdan.cc>

cmd/gogio/js_test.go

@@ -152,9 +152,3 @@ func (d *JSTestDriver) Click(x, y int) {
 	// TODO(mvdan): synchronize with the app instead
 	time.Sleep(200 * time.Millisecond)
 }
-
-func TestJS(t *testing.T) {
-	t.Parallel()
-
-	runEndToEndTest(t, &JSTestDriver{})
-}