[css-fonts] Drop bracket matching step from @font-face src: line parsing

[mozilla-apprentice]

A resolution was made for csswg-drafts/#6340.

[css-fonts] Drop bracket matching step from `@font-face` src: line parsing

• RESOLVED: Parse the value of src throwing out invalid parts like media queries and not like selectors. aka You split on the commas and throw out the pieces you don't understand not the whole thing.

Discussion.

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To file a bug automatically for these resolutions, add the bug label to the issue.

If no bug is needed, the issue can be closed.

[aethanyc]

The "RESOLVED" is a quote from other issue, not an actual resolution.