Performance marks incorrectly recorded for Evented trigger method

[mwhitworth]

After ae8e47d Without specifying any options relating to ember-perf-timeline - overriding the Evented trigger method will call the TriggerMixin to be called for all trigger calls in Evented in all cases. (This causes a large jump in memory usage for a complex application)

Perhaps the TriggerMixin should be only be registered for these Ember objects when any one of the ember-perf-timeline options are enabled.