The ornamental design for a chairarm, as shown and described.
FIG. 1 is a perspective view showing the left side and the rear of a chair arm which forms my new design, the broken lines of an arm pad and a chair being for illustrative purposes only and forming no part of my design;
FIG. 2 is a left side elevational view thereof;
FIG. 3 is a right 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;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is an enlarged perspective view showing the front, left side and rear thereof.