Emitter.start should Setting quantity Not Adding

I think Emitter.start should Setting quantity Not Adding, maybe "+=" is a mistake?

Author: nextht

src/particles/arcade/Emitter.js

@@ -434,7 +434,7 @@ Phaser.Particles.Arcade.Emitter.prototype.start = function (explode, lifespan, f
     else
     {
         this.on = true;
-        this._quantity += quantity;
+        this._quantity = quantity;
         this._counter = 0;
         this._timer = this.game.time.time + frequency * this.game.time.slowMotion;
     }