Is there a way to pass an argument to a Polymer function from an element attribute inside its ?
After searching a lot, I found what I think is the cleanest possible solution.
If the paper-button is inside a template, e.g.
[[item.text]]
Then the properties can be accessed via "model" property in event object passed to function.
itemTapped: function(oEvent){
// oEvent.model.get is the getter for all properties of "item" in your bound array
console.log(oEvent.model.get('item.task'));
}