The ornamental design for a towerdock, as shown and described.
FIG. 1 is a front view of the ornamental design for a tower dock;
FIG. 2 is a front, right side perspective view thereof;
FIG. 3 is a right-side view thereof;
FIG. 4 is a back view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is front, left side perspective view of the ornamental design for a tower dock, shown in a condition of use.
The broken lines on the tower dock depict portions of the tower dock that form no part of the claimed design. The broken lines in FIG. 8 showing a mobile phone depict environmental subject matter and form no part of the claimed design.