embed/internal/embedtest: use parenthesized vars for one test

The gofrontend code mishandled this case, so add it to the test.

Change-Id: I183b8fab57552320b04c4826c590b7c6d36b6548
Reviewed-on: https://go-review.googlesource.com/c/go/+/358836
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
diff --git a/src/embed/internal/embedtest/embed_test.go b/src/embed/internal/embedtest/embed_test.go
index b41359f..bfd94af 100644
--- a/src/embed/internal/embedtest/embed_test.go
+++ b/src/embed/internal/embedtest/embed_test.go
@@ -89,11 +89,13 @@
 	testDir(t, all, "testdata/i/j/k", "k8s.txt")
 }
 
-//go:embed testdata
-var testHiddenDir embed.FS
+var (
+	//go:embed testdata
+	testHiddenDir embed.FS
 
-//go:embed testdata/*
-var testHiddenStar embed.FS
+	//go:embed testdata/*
+	testHiddenStar embed.FS
+)
 
 func TestHidden(t *testing.T) {
 	dir := testHiddenDir