[ahoge]

Firefox's Brotli support is already done. Chrome's isn't.

By the way, new features are generally created this way. They are added to browsers way before they are standardized. You see, convincing the other browser vendors isn't easy. You need very compelling arguments.

Take WebP, for example. It provides massive benefits. Especially if you can use lossy RGBA instead of PNG32 (easily 80% smaller). And yet, Mozilla shows little interest in implementing it.