race condition in test: fetchPostBodyTypedArray

[ry]

Only happening occasionally - only observed on windows.

test fetchPostBodyTypedArray_permW0N1E0R0
HttpUser: connection closed
    at maybeError (deno/js/errors.ts:38:12)
    at handleAsyncMsgFromRust (deno/js/dispatch.ts:27:17)
test result: FAILED. 7 passed; 1 failed; 0 ignored; 0 measured; 206 filtered out
Error: There were 1 test failures.
    at setTimeout (file:///C:/deno/js/testing/testing.ts:110:13)
    at fire (deno/js/timers.ts:131:3)

ex: https://ci.appveyor.com/project/deno/deno/builds/20541747

[kt3k]

Note: My attempt #1535 (now reverted).

[bartlomieju]

Duplicate of #1228