text/v2: change the signature of NewMultiFace

Updates #2845

examples/mixedfont/main.go

@@ -74,7 +74,7 @@ func (g *Game) Update() error {
 			Size:   32,
 		}
 
-		g.face = text.NewMultiFace([]text.Face{en, ja})
+		g.face = text.NewMultiFace(en, ja)
 	}
 	return nil
 }

text/v2/multi.go

@@ -31,11 +31,10 @@ type MultiFace struct {
 }
 
 // NewMultiFace creates a new MultiFace from the given faces.
-func NewMultiFace(faces []Face) *MultiFace {
+func NewMultiFace(faces ...Face) *MultiFace {
-	m := &MultiFace{}
+	return &MultiFace{
-	m.faces = make([]Face, len(faces))
+		faces: faces,
-	copy(m.faces, faces)
+	}
-	return m
 }
 
 // Metrics implements Face.