Fixing issue #4198: VR deep-linking / VR navigation doesn't work.

[Artyom17]

Description:
Fixing issue #4198: VR deep-linking / VR navigation doesn't work.

Changes proposed:

• Canvas must have gl context associated with it for requestPresent to work;
• onVRDisplayPresentChange by spec is called only once for the first requestPresent (which might be called from the ondisplayactivate and can't init all the data); so, firing the second event "artificially".

[dmarcos]

It looks good to me. Just a small change and it's ready to go. Thank you very much for this and investigating the issue. Glad to have robust in-vr navigation again 👏

[dmarcos]

Awesome. Thank you!