The ornamental design for a doll dress, as shown and described.
FIG. 1 is an isometric top view of a doll dress showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof showing my design.
The broken lines in the drawings illustrating a doll depict an operational environment for the doll dress which forms no part of the claimed design. The broken lines shown on the article illustrate stitching which forms part of the claimed design.