Fix remaining icon_size references
Fix remaining icon_size references

icon_size was changed to pixel_size, yet references remained, causing
extra log data.

Additional change missed from already merged 70bc4db.

Daksh/sugar-toolkit-gtk3,sugarlabs/sugar-toolkit-gtk3,quozl/sugar-toolkit-gtk3,i5o/sugar-toolkit-gtk3,i5o/sugar-toolkit-gtk3,quozl/sugar-toolkit-gtk3,Daksh/sugar-toolkit-gtk3,quozl/sugar-toolkit-gtk3,sugarlabs/sugar-toolkit-gtk3,quozl/sugar-toolkit-gtk3,i5o/sugar-toolkit-gtk3,i5o/sugar-toolkit-gtk3,sugarlabs/sugar-toolkit-gtk3,Daksh/sugar-toolkit-gtk3