Auto merge of #22938 - asajeffrey:webvr-future-frame-data, r=paulrouget

Use webvr future_frame_data to avoid blocking the WebGL thread

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This PR fixes a potential deadlock caused by the WebGL thread being blocked on a VR device. Rather than blocking on the VR device, it forwards a future to the script thread, and then then script thread blocks.

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- [X] `./mach test-tidy` does not report any errors
- [X] These changes do not require tests because it's fixing a potential deadlock

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