I don't know when they did this, but Chrome also seems to remember form input when you back out, and re-fills the form if your reverse the backing out. That's a better solution than changing the shortcut because it works if you back out by other means, too, such as clicking the back button with the mouse or using the back gesture on a Magic Mouse.
Firefox does it to.
This has saved me many a time when I've accidentally done a back gesture on my Magic Mouse while composing an HN comment.
Sometimes, unless the flow is made of multiple pages of forms. Press back, you get to the previous form (with the fields now empty obviously), press forward, get a server 500 error.
In a nutshell, it feels like browser makers do their best to improve user experiences, and website designer do their best to ruin it again.
Firefox does it to.
This has saved me many a time when I've accidentally done a back gesture on my Magic Mouse while composing an HN comment.