can.compute change handler context should be the function not the can.Compute object

[daffl]

When binding to a can.compute in can.Control with a templated event handler the handler gets the instance of can.Compute not the compute function as it was in 2.1:

test('templated binding a compute', function() {
    var comp = can.compute(null);
    var Control = can.Control.extend({
        '{mycompute} change': function(value) {
            ok(typeof value === 'function', 'Compute change value is a function');
        }
    });

    new Control('#qunit-fixture', {
        mycompute: comp
    });

    comp('test');
});

[daffl]

Here is a simpler test:

test('compute change handler context is set to the function not can.Compute', function() {
    var comp = can.compute(null);

    comp.bind('change', function() {
        equal(typeof this, 'function');
    });

    comp('test');
});

Basically the change handler context needs to be the can.compute function (which is what it used to be in 2.1) not the new can.Compute object.