getValueFromGivenConfig_(valueName, configObject) {
    let objOn = configObject;
    let valueNameOn = valueName;
    try {
      while (valueNameOn) {
        // Split using a regex that only matches the first period.
        const split = valueNameOn.split(/\.(.+)/);
        if (split.length == 3) {
          valueNameOn = split[1];
          objOn = objOn[split[0]];
        } else {
          return objOn[split[0]];
        }
      }
    } catch (e) {
      // Ignore errors
    }
    return undefined;
  }
Recovers the value from the given config field, from an arbitrary config
object.
This uses the same syntax as setting a single configuration field.
@param {string} valueName
@param {?shaka.extern.PlayerConfiguration} configObject
@return {*}
@private