CSS `min()` function breaks syntax highlighting

[alexr00]

Originally from @stefanprobst in microsoft/vscode#134243

Does this issue occur when all extensions are disabled?: Yes

• VS Code Version: 1.60.2 (with --disable-extensions)
• OS Version: Ubuntu 20.04

Using CSS min() or clamp() functions seems to break syntax highlighting.

Steps to Reproduce:

1. Copy-paste the following css rule, and observe the different highlighting for the first 1fr and the second 1fr value:

.test {
  grid-template-columns: 1fr min(1024px, 100%) 1fr;
}