Extinguishing your teammates with Gas Passer should reduce its cooldown by 20 %, similiarly to Mad Milk or Jarate

[JohanSchuber]

Since both Jarate and Mad Milk have this upside, it should be consistent with other throwables.
Alternatively, extinguishing could also build 20 % of its meter, instead of reducing cooldown, since Gas Passer does not work exactly as Jarate, as it can both build its meter over time and can also have it build by dealing damage.