The ornamental design for the windscreen wiper, as shown and described.
FIG. 1 is a perspective view of a windscreen wiper showing our new design.
FIG. 2 is a front view thereof.
FIG. 3 is a rear view thereof.
FIG. 4 is a magnified left side view thereof.
FIG. 5 is a magnified right side view thereof.
FIG. 6 is a top plan view thereof.
FIG. 7 is a bottom plan view thereof.
FIG. 8 is a detailed view of area 8 in FIG. 2. The other end is the same.
FIG. 9 is a detailed view of area 9 in FIG. 6. The other end is the same.
FIG. 10 is a detailed view of area 10 in FIG. 7. The other end is the same; and,
FIG. 11 is a detailed view of area 11 in FIG. 10.
The broken lines illustrating areas of the detail views form no part of the claimed design. The remaining broken lines illustrate portions of the windscreen wiper that form no part of the claimed design.