Bypass a thread-hop by using StartImmediateAsTask

Author: abelbraaksma

src/FSharp.Control.TaskSeq/AsyncExtensions.fs

@@ -8,5 +8,5 @@ module AsyncExtensions =
 
         member _.For(source: TaskSeq<'T>, action: 'T -> Async<unit>) =
             source
-            |> TaskSeq.iterAsync (action >> Async.StartAsTask)
+            |> TaskSeq.iterAsync (action >> Async.StartImmediateAsTask)
             |> Async.AwaitTask

src/FSharp.Control.TaskSeq/TaskSeqBuilder.fs

@@ -648,7 +648,7 @@ module HighPriority =
             ResumableTSC<'U>(fun sm ->
                 let mutable awaiter =
                     Async
-                        .StartAsTask(computation, cancellationToken = sm.Data.cancellationToken)
+                        .StartImmediateAsTask(computation, cancellationToken = sm.Data.cancellationToken)
                         .GetAwaiter()
 
                 let mutable __stack_fin = true