Current behavior:

In a debug build using speedy, using vendor specific css-prefixes such as webkit will cause errors to be written to the console in firefox.

To reproduce:

I don't succeed with a CodeSandbox-example since I can't figure out how to set speedy to true in that environment.

1. Define a component using a vendor-specific prefix such as "::-webkit-scrollbar-track:hover{border-width:0.3125rem;background-color:rgba(255, 255, 255, 0.15625);}
2. Set speedy true on the CacheProvider
3. Do a non-production build
4. Run the app in firefox
5. An error like the following There was a problem inserting the following rule: "::-webkit-scrollbar-track:hover{border-width:0.3125rem;background-color:rgba(255, 255, 255, 0.15625);}" DOMException: An invalid or illegal string was specified

Expected behavior:

No errors in the console

Environment information:

"@emotion/react": "11.11.1",
"@emotion/styled": "11.11.0",
"react": "18.2.0",
"react-dom": "18.2.0",