[Cocoa] Have PointerLock use native APIs

Hi Jens, this is the pre-requirement of implementing pointer lock unadjuestedmovement support on macOS (bug 1829401).
Could you help to find someone reviewing widget changes? I flag :mstange as well since he has reviewed some patches of bug 1829401, but I am not sure if he would review this as well or maybe someone from your team can help. Thanks!

nm, mstange has reviewed. :)

Backed out for causing failures at nsCocoaWindow.

Backout link: https://hg.mozilla.org/integration/autoland/rev/9e9ea9f30d31

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&group_state=expanded&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel&revision=0a29d021c3c2354558c8aa036d0b0d4d4c8a4587&selectedTaskRun=H3OLGa_lRL-HQ9G5R_W4Fw.0

Failure log: https://treeherder.mozilla.org/logviewer?job_id=564415579&repo=autoland&task=H3OLGa_lRL-HQ9G5R_W4Fw.0&lineNumber=37998

(In reply to Edgar Chen [:edgar] from comment #3)

nm, mstange has reviewed. :)

Yeah, :spohl told me he was faster...

(In reply to Atila Butkovits from comment #6)

Backed out for causing failures at nsCocoaWindow.

Backout link: https://hg.mozilla.org/integration/autoland/rev/9e9ea9f30d31

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&group_state=expanded&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel&revision=0a29d021c3c2354558c8aa036d0b0d4d4c8a4587&selectedTaskRun=H3OLGa_lRL-HQ9G5R_W4Fw.0

Failure log: https://treeherder.mozilla.org/logviewer?job_id=564415579&repo=autoland&task=H3OLGa_lRL-HQ9G5R_W4Fw.0&lineNumber=37998

Okay, it turns out the assertion I added is too strict. The LockNativePointer() can be called multiple times while pointer lock element is changed, this is the behavior that we have right now, and I don't want to change that at the moment. I guess we would need some tweak later to avoid that.

https://hg.mozilla.org/mozilla-central/rev/0283215ae507

firefox-beta Uplift Approval Request

• User impact if declined/Reason for urgency: The is the pre-requirement to implement pointer lock unadjustedMovement on macOS.
• Code covered by automated testing?: no
• Fix verified in Nightly?: yes
• Needs manual QE testing?: no
• Steps to reproduce for manual QE testing: None
• Risk associated with taking this patch: low
• Explanation of risk level: The pref is enabled only on Nightly for now.
• String changes made/needed?: None
• Is Android affected?: yes

Co-authored-by: Noah Peterson <noahbpeterson1997@gmail.com>

Original Revision: https://phabricator.services.mozilla.com/D297981