Input [type = "submit" i] - What is "i" and this syntax

Question

While checking an item in Chrome, I came across this:

input[type="submit" i]:active

This is part of the Chrome UI user style sheet. I have been engaged in web development since 2002, and I had never noticed or noticed before. It doesn't even look like what I was thinking about syntax. Is this specific to Chrome? Is there any W3C documentation there? Trying to mess with him, it looks like this is not like what is written:

input[type="submit"]:active

I am actively searching the Internet and have achieved nothing. If anyone knows, I would appreciate a response.

PS The only thing I could think of was that it meant “inner”, although I just don't know.