Move the window.orientation stuff to the orientation spec?

[karlcow]

@miketaylr, should we just move the window.orientation stuff to the orientation spec?
w3c/screen-orientation#249

window.orientation is widely used (I think) so we probably can't get rid of it (and it's interoperable)... wdyt? What's been commonly done in these cases?

Originally posted by @marcoscaceres in #223 (comment)

[karlcow]

As I said to @marcoscaceres in private, this is the goal of the compat spec. It should be transitory as much as possible. And if something needs can be defined in a proper spec, it's better.

[miketaylr]

We've done this before (WebKitCSSMatrix comes to mind), so no issue. We can just leave a pointer to its new home to not break cool URIs, e.g. https://compat.spec.whatwg.org/#webkitcssmatrix-interface

[marcoscaceres]

Sounds like a plan....