The ornamental design for a frame for trolley, as shown and described.
FIG. 1 is an isometric view of a frame for a trolley according to an embodiment of the present invention, taken from the front and to the left of the frame. The portions of the trolley not visible in FIG. 1 form no part of the claim.
FIG. 2 is an isometric view of the frame shown in FIG. 1, taken from the rear and to the left of the frame. The portions of the frame not visible in FIGS. 1 and 2 form no part of the claim; and,
FIG. 3 is an isometric view of a frame for a trolley as shown in FIG. 1, wherein the frame is collapsed.