I claim the ornamental design for a window seal, as shown and described.
FIG. 1 is a perspective view of a window seal, showing my new design in an installed configuration;
FIG. 2 is a front elevational view thereof, illustrated in a flat configuration;
FIG. 3 is a rear elevational view of FIG. 2;
FIG. 4 is a left-side elevational view of FIG. 2, the right-side elevational view being a mirror image thereof; and,
FIG. 5 is a top plan view of FIG. 2, the bottom plan view being a mirror image thereof.
The broken lines showing a window and blinds in FIG. 1 depict environmental matter and form no part of the claimed design. The remaining broken lines depict that the design has an indefinate height and width.