propogate cancellation tokens to reactor queue (fix)

Author: dsyme

src/fsharp/vs/ServiceDeclarations.fs

@@ -1281,7 +1281,7 @@ type FSharpDeclarationListItem(name, glyph:int, info) =
             match info with
             | Choice1Of2 (items, infoReader, m, denv, reactor:IReactorOperations, checkAlive) -> 
                     // reactor causes the lambda to execute on the background compiler thread, through the Reactor
-                    reactor.EnqueueAndAwaitOpAsync ("DescriptionTextAsync", fun () -> 
+                    reactor.EnqueueAndAwaitOpAsync ("DescriptionTextAsync", fun _ct -> 
                           // This is where we do some work which may touch TAST data structures owned by the IncrementalBuilder - infoReader, item etc. 
                           // It is written to be robust to a disposal of an IncrementalBuilder, in which case it will just return the empty string. 
                           // It is best to think of this as a "weak reference" to the IncrementalBuilder, i.e. this code is written to be robust to its