_cssTextToMap(text, replaceInitialOrInherit = false) {
    let props = text.split(';');
    let property, value;
    let out = {};
    for (let i = 0, p, sp; i < props.length; i++) {
      p = props[i];
      if (p) {
        sp = p.split(':');
        // ignore lines that aren't definitions like @media
        if (sp.length > 1) {
          property = sp[0].trim();
          // some properties may have ':' in the value, like data urls
          value = sp.slice(1).join(':');
          if (replaceInitialOrInherit) {
            value = this._replaceInitialOrInherit(property, value);
          }
          out[property] = value;
        }
      }
    }
    return out;
  }
"parse" a mixin definition into a map of properties and values
cssTextToMap('border: 2px solid black') -> ('border', '2px solid black')
@param {string} text
@param {boolean=} replaceInitialOrInherit
@return {!Object<string, string>}