Add can-lock-orientation CSS media feature

[marcoscaceres]

• Implement can-lock-orientation media feature for Issue #206
• Add privacy considerations to prevent fingerprinting through user preferences
• Include examples showing CSS and JavaScript usage
• Update abstract to mention CSS media features

Closes #206

The following tasks have been completed:

• [ ] Modified Web platform tests (link to pull request)

Implementation commitment:

• [ ] WebKit (https://bugs.webkit.org/enter_bug.cgi)
• [ ] Chromium (https://bugs.chromium.org/p/chromium/issues/detail?id=)
• [ ] Gecko (https://bugzilla.mozilla.org/show_bug.cgi?id=)

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Preview | Diff

[emilio]

Why is this a media feature out of curiosity? Feels rather odd, is there any precedent for these can-*?

[marcoscaceres]

@Emilio, it's where we landed with: https://github.com/w3c/screen-orientation/issues/206

But yes, the name is terrible.