The ornamental design for a cradle, as shown and described.
FIG. 1 is a rear perspective view of a cradle, showing my new design;
FIG. 2 is a rear elevation view of the cradle;
FIG. 3 is a top plan view of the cradle;
FIG. 4 is a left elevation view of the cradle, with the right side elevation view being a mirror image of the left elevation view;
FIG. 5 is a bottom plan view of the cradle; and,
FIG. 6 is a left elevation view of the cradle, shown in a folded configuration, with the right elevation view being a mirror image of the left elevation view.
The broken lines shown in the figures represent environment and form no part of the claimed design.