The ornamental design for a markerlight, as shown and described.
FIG. 1 is an isometric view of a marker light, showing our new design.
FIG. 2 is a front elevational view thereof.
FIG. 3 is a rear elevational view thereof.
FIG. 4 is a right side elevational view thereof.
FIG. 5 is a left side elevational view thereof.
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
Stippling in the drawings represents the three-dimensional contours of the design, and is not intended to indicate surface decoration. The broken lines shown in the drawings depict portions of the marker light that form no part of the claimed design.