worker: make MessagePort `uv_async_t` inline field
It’s not obvious why this was a heap allocation in the first place,
but it’s unneccessary. Most other HandleWrap
s also store the
libuv handle directly.
(This is going to have a minor merge conflict with https://github.com/nodejs/node/pull/26099 so I’d wait until after that one lands before merging this.
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
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