Describe the bug
I had a feeling that this issue issue may have been raised before but I can't find it.

When you enter a url for a button, you can't hit the Return key to apply your changes.

On top of that, if you type a url without the https:// it displays a random result from your site and when you hit Return, it actually selects that result instead of using the url you typed

To Reproduce
Steps to reproduce the behavior:

1. Add Button Block
2. Type google.com into the URL field
3. Hit return key to apply changes

Expected behavior
I should be able to simply enter a URL and hit Enter/Return to apply the changes

Screenshots

macOS Sierra 10.12.1 (16B2659)
Firefox Quantum 60.0 (64-bit)
WordPress 4.9.6
Gutenberg 2.9.0