FIG. 1 is a perspective view of a container cap showing my new design; FIG. 2 is a top plan view of a container cap showing my new design; FIG. 3 is a right side view of a container cap showing my new design; FIG. 4 is a cross-sectional view along line 4-4 of FIG. 3. FIG. 5 is a front end view of the container cap showing my new design; and, FIG. 6 is a bottom plan view of a container cap showing my new design.