Apparently all browsers support this as of IE9 testing:
Note, the current DOM L3 Events spec mentions the following (but omits "Events" as a valid compatibility string):
*For backward compatibility reason, "UIEvents", "MouseEvents", "MutationEvents", and "HTMLEvents" feature names are valid values for the parameter eventInterface and represent respectively the interfaces UIEvent, MouseEvent, MutationEvent, and Event, and the characters 'a'..'z' are considered equivalent to the characters 'A'..'Z'.
The request is to add a mapping for the string "Events" to the Event interface for interop purposes.
Interesting! Fixed in DOM: https://bitbucket.org/ms2ger/dom-core/changeset/edc7186a302a
Added a test:
Interestingly, webkit only supports the title-case versions.
Updated the backward compatibility list in DOM3 Events as well.
As the opener, I'm satisfied with this change :)