The ornamental design for doll, as shown and described.
1. Doll
1.1 : Front
1.2 : Back
1.3 : Left
1.4 : Right
1.5 : Top
1.6 : Bottom
1.7 : Perspective
Fig. 1.1 is a front elevation view of doll showing our new design; fig. 1.2 is a back elevation view thereof; fig. 1.3 is a left side elevation view thereof; fig. 1.4 is a right side elevation view thereof; fig. 1.5 is a top plan view thereof; fig. 1.6 is a bottom plan view thereof; and fig. 1.7 is a perspective view thereof.