Moving XHR, DOM Parsing and Pointer Lock to Github

Hi All,

All of WebApps' specs are now on Github except XHR, DOM P&S and Pointer 
Lock and we would like to move/import these three specs to GH too.

Xiaoqian and I will do the import and we don't expect it to affect you.

After the move is complete, your (obsolete) EDs on Hg will be redirected 
to their github equivalent and available on the gh-pages branch as 
"index.html" (thus directly viewable as, for example, 
<https://w3c.github.io/pointerlock/>). The Hg repos will be configured 
as read-only.

If you have any questions or concerns, please let us know.

-Thanks, Art and Xiaoqian