The ornamental design for an ledlightbulbfilament, as shown and described.
FIG. 1 is an exploded view of an LED light bulb filament showing our new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a perspective view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a left side elevational view thereof;
FIG. 6 is a right side elevational view thereof; and,
FIG. 7 is a rear elevational view thereof.
The structural features depicted by broken lines have been shown for the purpose of illustrating portions of the light that form no part of the claimed design.