worker: allow synchronously draining message ports
In combination with Atomics, this makes it possible to implement
generic synchronous functionality, e.g. importScript()
, in Workers
purely by communicating with other threads.
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
documentation is changed or added -
commit message follows commit guidelines