PSA: Origin Trials binding code now being automatically generated

[Ian Clelland]

Good news everyone!

I landed a patch yesterday to start generating the V8 bindings code for origin-trial-enabled features directly from the IDL files.

If you've worked on an origin trial before, you've probably experienced the pain of manually editing ConditionalFeaturesFor{Core/Modules}.cpp, and of ensuring that you get the right objects and interfaces instantiated and mentioned in all the right places.

As of today, though, that should all be gone. Using the [OriginTrialEnabled] IDL extended attribute to name a feature from RuntimeEnabledFeatures should now be sufficient to have all of the bindings code automatically written for you.

(You can still use OriginTrials::myAwesomeFeatureEnabled(Document*) in Blink code to gate any other behaviour changes unrelated to bindings -- and in general, see docs/origin_trials_integration.md for more how-to info.)

If you are working on such a feature now, and you notice any oddities (interfaces not being attached correctly, with or without a trial token), let me know, file a bug against Internals>OriginTrials, and I'll take a look.