The ornamental design for a trolley, as shown and described.
FIG. 1 is a top, front right perspective view of a trolley showing my new design;
FIG. 2 is a top, front perspective view thereof in an alternate position; and,
FIG. 3 is a side view thereof; wherein the alternate side view is a mirror image thereof.
The broken lines showing the cup in FIGS. 1, 2 and 3 are for the purpose of illustrating the environment and form no part of the claimed design. The rest of the broken lines in the figures are to show portions of the trolley and form no part of the claimed design.