wasm test failure: System.IO.Tests.FileStream_SafeFileHandle.ThrowWhenHandlePositionIsChanged_async

[antonfirsov]

Filed on mono/wasm (net5.0-Browser-Release-wasm-Mono_Release-Ubuntu.1804.Amd64.Open) in #40841:
https://dev.azure.com/dnceng/public/_build/results?buildId=772623&view=ms.vss-test-web.build-test-results-tab&runId=24126412&paneView=debug

With PlatformNotSupportedException: Cannot wait on monitors on this runtime.

Currently I'm rerunning the tests, but since FileSystem and System.Private.Corelib doesn't have a dependency on System.Net.Primitives, I don't think it can be related to my PR.

[danmoseley]

Assert.Throws() Failure\nExpected: typeof(System.IO.IOException)\nActual: typeof(System.PlatformNotSupportedException): Cannot wait on monitors on this runtime.\n---- System.PlatformNotSupportedException : Cannot wait on monitors on this runtime.

Stack trace
   at System.Threading.Monitor.ObjWait(Boolean exitContext, Int32 millisecondsTimeout, Object obj)
   at System.Threading.Monitor.Wait(Object obj, Int32 millisecondsTimeout, Boolean exitContext)
   at System.Threading.Monitor.Wait(Object obj, Int32 millisecondsTimeout)
   at System.Threading.ManualResetEventSlim.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Threading.Tasks.Task.SpinThenBlockingWait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Threading.Tasks.Task.InternalWaitCore(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Threading.Tasks.Task.InternalWait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.IO.FileStream.Read(Byte[] array, Int32 offset, Int32 count)
   at System.IO.Tests.FileStream_SafeFileHandle.<>c__DisplayClass5_0.<ThrowWhenHandlePositionIsChanged>b__1()
----- Inner Stack Trace -----
   at System.Threading.Monitor.ObjWait(Boolean exitContext, Int32 millisecondsTimeout, Object obj)
   at System.Threading.Monitor.Wait(Object obj, Int32 millisecondsTimeout, Boolean exitContext)
   at System.Threading.Monitor.Wait(Object obj, Int32 millisecondsTimeout)
   at System.Threading.ManualResetEventSlim.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Threading.Tasks.Task.SpinThenBlockingWait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Threading.Tasks.Task.InternalWaitCore(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Threading.Tasks.Task.InternalWait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.IO.FileStream.Read(Byte[] array, Int32 offset, Int32 count)
   at System.IO.Tests.FileStream_SafeFileHandle.<>c__DisplayClass5_0.<ThrowWhenHandlePositionIsChanged>b__1()