wrong handling of punctuation between comma separated function calls

[papandreou]

• Webpack Version: n/a
• Operating System (or Browser): Ubuntu Linux 18.10
• Node Version: 10.16.2
• postcss-values-parser Version: 3.0.5

How Do We Reproduce?

require('postcss-values-parser').parse('local(foo),local(bar)')

Expected Behavior

Should come out as a func node followed by a punctuation node (the comma) and another func node.

Actual Behavior

Root {
  raws: { semicolon: false, after: '' },
  type: 'root',
  nodes:
   [ Func {
       raws: [Object],
       name: 'local',
       type: 'func',
       isColor: false,
       nodes: [Array],
       parent: [Circular],
       source: [Object],
       params: '(foo)' },
     Func {
       raws: [Object],
       name: ',local', // <-- that comma should have been its own token
       type: 'func',
       isColor: false,
       nodes: [Array],
       parent: [Circular],
       source: [Object],
       params: '(bar)' } ],
  source: [...]
}

I haven't done a thorough reading of the CSS syntax module spec, but I'm fairly sure that the spacing around the comma is optional. I've also seen cssnano compress font-family values to omit it between local(...) tokens like these.