examples/highdpi: remove an old comment

examples/highdpi/main.go

@@ -54,10 +54,6 @@ func NewGame() *Game {
 }
 
 func (g *Game) Update() error {
-	// TODO: DeviceScaleFactor() might return different values for different monitors.
-	// Add a mode to adjust the screen size along with the current device scale (#705).
-	// Now this example uses the device scale initialized at the beginning of this application.
-
 	if g.highDPIImage != nil {
 		return nil
 	}