Origin Trial support

[rentallect]

Today we ask/expect browZer users to first surf to chrome://flags, then search for the JSPI. flag, then enable it... and then we hope that Chrome doesn't reset that flag when it does the auto-updates.

This is fraught with friction, and frustration, especially when Chrome keeps resetting the flag, and the Edge browser recently stopped rendering the JSPI flag at all!

We should transition to Origin Trial enablement of the JSPI flag.

Doing so will make enablement of the JSPI flag automatic/transparent for users... AND... it works with Chrome, Brave and Edge.