Not likely.
Skittles and watermelon tea are 2 of the 3 ingredients in "purple drank" or "purple lean". The third ingredient is cough syrup, either with codeine or Dextromethorphan (DM). Martin's Facebook page had an extensive discussion about the recipe.
Martin's liver autopsy showed signs of damage that could be caused by lean/drank abuse. DM abuse also can cause aggressive/paranoid behavior.
And Trayvon was probably trying really hard to be “cool.” There’s no reason to use Skittles and flavored tea if the object is merely to quaff down so much dextromethorphan that you get looey in the head. In fact the extra liquid might make it more difficult to get the desired dose.