storage: remove a todo

Change-Id: I22d8a0b31604155671b215222b3dfad361125642
Reviewed-on: https://code-review.googlesource.com/31790
Reviewed-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
diff --git a/storage/storage.go b/storage/storage.go
index d710f3d..ae663d3 100644
--- a/storage/storage.go
+++ b/storage/storage.go
@@ -1065,5 +1065,3 @@
 	headers.Set("x-goog-"+cs+"encryption-key-sha256", base64.StdEncoding.EncodeToString(keyHash[:]))
 	return nil
 }
-
-// TODO(jbd): Add storage.objects.watch.