Double clicks are also possible with PhantomJS.
Recommended
This is adapted from the answer of stovroz and triggers a native dblclick including the mousedown, mouseup and click events (two of each).
var rect = page.evaluate(function(selector){
    return document.querySelector(selector).getBoundingClientRect();
}, selector);
page.sendEvent('doubleclick', rect.left + rect.width / 2, rect.top + rect.height / 2);
Other ways
The following two ways only trigger the dblclick event, but not the other events that should precede it.
Adapted from this answer of torazaburo:
page.evaluate(function(selector){
    var el = document.querySelector(sel);
    var ev = document.createEvent("MouseEvent");
    ev.initMouseEvent(
        'dblclick',
        true /* bubble */, true /* cancelable */,
        window, null,
        0, 0, 0, 0, /* coordinates */
        false, false, false, false, /* modifier keys */
        0 /*left*/, null
    );
    el.dispatchEvent(ev);
}, selector);
Adapted from this answer of Jobins John:
page.evaluate(function(selector){
    var el = document.querySelector(sel);
    var e = document.createEvent('MouseEvents');
    e.initMouseEvent('dblclick', true, true, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
    el.dispatchEvent(e);
}, selector);
Full test script