I claim the ornamental design for an article container, as shown and described.
FIG. 1 is a top left front perspective view of an article container.
FIG. 2 is a right side elevational view thereof.
FIG. 3 is a left side elevational view thereof.
FIG. 4 is a rear elevational view thereof.
FIG. 5 is a front elevational view thereof.
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The shading lines shown in the drawings represent the approximate three-dimensional contour of the design, and are not intended to indicate surface decoration.