fix(browserTrigger): do not use document.createEvent method

Firefox 23 has deprecated the use of createEvent for transition and
animation events.  We must now use `new TransitionEvent()` and
`new AnimationEvent()` if they are available.

But of course IE doesn't support this format correctly so we must wrap
the attempt in a try block and revert to document.createEvent if necessary..

Author: petebacondarwin

src/ngScenario/browserTrigger.js

@@ -96,8 +96,13 @@
           evnt.initEvent(eventType, false, true);
         }
         else {
-          evnt = document.createEvent('TransitionEvent');
-          evnt.initTransitionEvent(eventType, null, null, null, eventData.elapsedTime);
+          try {
+            evnt = new TransitionEvent(eventType, eventData);
+          }
+          catch(e) {
+            evnt = document.createEvent('TransitionEvent');
+            evnt.initTransitionEvent(eventType, null, null, null, eventData.elapsedTime);
+          }
         }
       }
       else if(/animationend/.test(eventType)) {
@@ -106,8 +111,13 @@
           evnt.initEvent(eventType, false, true);
         }
         else {
-          evnt = document.createEvent('AnimationEvent');
-          evnt.initAnimationEvent(eventType, null, null, null, eventData.elapsedTime);
+          try {
+            evnt = new AnimationEvent(eventType, eventData);
+          }
+          catch(e) {
+            evnt = document.createEvent('AnimationEvent');
+            evnt.initAnimationEvent(eventType, null, null, null, eventData.elapsedTime);
+          }
         }
       }
       else {