The ornamental design for a lightbar, as shown and described.
FIG. 1 is a top front perspective view of a light bar;
FIG. 2 is a front elevation view thereof; the rear elevation view being a mirror image thereof;
FIG. 3 is a left elevation view thereof; the right elevation view being a mirror image thereof;
FIG. 4 is a top elevation view thereof;
FIG. 5 is a bottom elevation view thereof;
FIG. 6 is a section view thereof, taken along line 6-6 in FIG. 4;
FIG. 7 is an enlarged partial section view thereof, taken along line 7-7 in FIG. 6; and,
FIG. 8 is an enlarged partial section view thereof, taken along line 8-8 in FIG. 7.
The broken dashed lines shown in the drawings illustrate portions of the light bar that form no part of the claimed design.
The claimed design is shown with a symbolic break in its length. The appearance of any portion of the article between the break lines forms no part of the claimed design.