Reduce scheduler serialization overhead

[developit]

In the process of switching to MessageChannel, it seems the postMessage call was modified to pass "*" (originally the target origin value from window.postMessage). This actually ends up triggering serialization, whereas passing undefined bypasses.

To save some investigation, passing a Number like 0 still incurs serialization overhead - undefined has special behavior.

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[sebmarkbage]

what about passing zero arguments?

[bvaughn]

what about passing zero arguments?

postMessage errors if you don't provide exactly 1 argument.

[acdlite]

What about null? Would that work? We like to use null if it's intentional.

I'll go ahead and merge, though. Thanks Jason!

[developit]

I admit I hadn't had time to check null. I need to verify with Mathias but I don't think it triggers the bypass. Source is here:
https://cs.chromium.org/chromium/src/third_party/blink/renderer/bindings/core/v8/script_value.h?type=cs&g=0&l=74

[sophiebits]

I didn’t think IsEmpty would return true for undefined; was this observably faster?

[sebmarkbage]

@developit For the formality, mind asking to be added to our CLA?

[developit]

Yup, working on it!

@sophiebits yes - consistently 5x faster. I'll set up a proper benchmark.

[sophiebits]

:o

[developit]

Update on the CLA - I was told to just sign as an individual, which I've just done.