Add missing tests for default values of event constructors
https://bugs.webkit.org/show_bug.cgi?id=108885

Reviewed by Adam Barth.

Spec: https://dvcs.w3.org/hg/d4e/raw-file/tip/source_respec.htm#constructor-keyboardevent

* fast/events/constructors/keyboard-event-constructor-expected.txt:
* fast/events/constructors/keyboard-event-constructor.html:
* fast/events/constructors/mouse-event-constructor-expected.txt:
* fast/events/constructors/mouse-event-constructor.html:
* fast/events/constructors/wheel-event-constructor-expected.txt:
* fast/events/constructors/wheel-event-constructor.html:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@141856 268f45cc-cd09-0410-ab3c-d52691b4dbfc