We claim the ornamental design for cookie mat for placement of cookie dough, as shown.
FIG. 1 is a perspective view of a design element for baking mats that directs the correct placement of cookie dough on a baking mat and describes how large the cookie will be once baked;
FIG. 2 is a top plan view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a right side elevation view thereof;
FIG. 5 is a left side elevation view thereof;
FIG. 6 is a rear elevation view thereof; and,
FIG. 7 is a bottom view thereof.
The broken line showing a baking mat is included for the purpose of illustrating the graphic in context and forms no part of the claimed design.