We do not have coreboot specific changes to the syntax highlighting code (e.g. this is stock Gerrit). 2.16.7 had a number of changes in their syntax highlighting though, and typically Chromium is not running on a release build but something in between releases or highly customized.
Ah, okay. I think it's this: https://bugs.chromium.org/p/gerrit/issues/detail?id=10658
That still doesn't explain why it's not matching braces, but I guess the parser may have always been broken and we just didn't notice because it uses the same color for so many things.