Fix code relating to cookies

internal/styles/fallback/wintergreen.go

@@ -1,6 +1,5 @@
 package fallbackStyle
 
-import "io"
 import "bytes"
 import "image"
 import _ "embed"
@@ -47,12 +46,6 @@ var borderColorShade    = [4]color.Color { colorShade,       colorShade,     col
 //go:embed assets/atlas.png
 var atlasBytes []byte
 
-type closerCookie struct { io.Closer }
-func (cookie closerCookie) Close () { cookie.Closer.Close() }
-func newCloserCookie (closer io.Closer) event.Cookie {
-	return closerCookie { Closer: closer }
-}
-
 // New returns Wintergreen, the default Tomo style. It is neutral-gray with
 // green and turquoise accents.
 func New () (*style.Style, event.Cookie) {
@@ -66,7 +59,7 @@ func New () (*style.Style, event.Cookie) {
 	textureHandleVertical   := atlasTexture.SubTexture(image.Rect(28,  0, 29,  2))
 	textureHandleHorizontal := atlasTexture.SubTexture(image.Rect(28,  0, 30,  1))
 
-	cookie := event.MultiCookie(newCloserCookie(atlasTexture))
+	cookie := event.MultiCookie(atlasTexture)
 
 rules := []style.Rule {
 	// *.*