The ornamental design for a slider for slidefastener, as shown and described.
FIG. 1 is a first perspective view of the front, bottom and right side of a slider for slide fastener showing my new design;
FIG. 2 is a second perspective view of the rear, top and left side thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a right side view thereof, the left side view being mirror image thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines shown are included for the purpose of illustrating the unclaimed portions of the slider for slide fastener and form no part of the claimed design.