The ornamental design for a supportinglegassembly, as shown and described.
FIG. 1 is a front perspective view of a supporting leg assembly showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a side elevational view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof; and,
FIG. 6 is a perspective view of the supporting leg assembly installed with a table and a substrate in use.
The broken lines immediately adjacent to claim as shown in the drawings represent the boundaries of the claimed design and form no part thereof. All other broken lines are directed to environment and form no part of the claimed design.