Jss: [jss-plugin-vendor-prefixer]: @keyframes rule errors because of a typo in onProcessRule()

[synchronos-t]

__Describe the bug:__
When adding a @keyframes rule, an error is thrown in css-vendor module's supportedKeyframes(key), because the key is undefined. This is due to a typo in the jssVendorPrefixer().onProcessRule(rule), where an undefined parameter atRule.at is passed, instead of the correct one atRule.key (I assume should be). Due to #888.

Here's a direct link: https://github.com/cssinjs/jss/blob/4168b8872c94dcab64d3ab4087c9e12683d960ca/packages/jss-plugin-vendor-prefixer/src/index.js#L14

__Codesandbox link:__
https://codesandbox.io/s/pjr11ykj30

__Versions:__

• jss: 9.8.7
• jss-plugins: 10.0.0-alpha.7
• Browser [e.g. chrome, safari]: Chrome 77, Firefox 66
• OS [e.g. Windows, macOS]: Windows 10

[synchronos-t]

OK, I believe this is just due to the different jss and jss-plugins-* versions. When just running npm i jss and npm i jss-preset-default those are the ones you get...

[sweetcoco]

@synchronos-t How did you resolve this? what versions did you end up using for each package?

[synchronos-t]

Just installed [email protected]. It's compatible with all the new jss-plugin-* packages, I believe, which are all at 10.0.0-alpha.7 in NPM at the moment, I think.

[sweetcoco]

@synchronos-t Thank you!