There is a hack to get around this. You can manually gzip your files before uploading them (or have a process that does this automatically). You can have 2 folders in your bucket (e.g. bucket/gzip/ and bucket/nongzip/). You include one Javascript file that is gzipped at the top of your web pages and in this file set a variable (e.g. var gzipEnabled = true). If the browser supports gzip, this variable will be set on your page. If not, the file will be gibberish, and the variable will not be set. You can then check for the value of this variable when including other assets on the page, and request them from the appropriate folder. Of course you have to weigh whether this approach has other performance drawbacks and whether the additional dev time is worth it.