code: function removePhaseTrigger(priv, target, propertyName) {
    var property = propertyName || 'transform';
    check(property, 'property').is.aString();
    var triggerElements = priv.phaseTriggers.get(property);
    check(target, 'target').is.instanceOf(EventTarget).and.is.oneOf(triggerElements, 'phase triggers')();
  
    triggerElements.splice(triggerElements.indexOf(target), 1);
  }
docs: Removes passed target from phase triggers.
  
  @param {Node} target that will no longer be used as a phase trigger
  @param {String} transitionProperty that will no longer be a trigger (optional, defaults to 'transform')
  @precondition given pair of **target** and **propertyName** is registered as phase trigger
  
  @fqn Phaser.prototype.removePhaseTrigger