lib.d.ts: Incorrect MessageEvent constructor signature.

[jduc88]

Description:

MessageEvent constructor signature should be same as base Event class ie.

new(type: string, eventInitDict?: EventInit): MessageEvent;

instead of,

new()

Documentation:

http://www.javascripture.com/MessageEvent

Error message on chrome:

TypeError: Failed to construct 'MessageEvent': An event name must be provided.

[martinduparc]

This is a problem for progressevent too. Looking at #2314 @mhegazy talks about how some definitions are auto generated from the IE references. Looking at https://msdn.microsoft.com/en-us/library/windows/apps/hh466083.aspx, the progressevent seems fine so I am not sure what to do.

[mhegazy]

@zhengbli can you take a look.

[zhengbli]

Confirmed on Chrome and Firefox that both MessageEvent and ProgressEvent has a required parameter and an optional EventInit dictionary. IE and Edge both don't support the constructor, with or without parameters. I think we do need to change the signatures.

[zhengbli]

Fixed by #4469