Remove check for PS6 in startup sequence

Author: andyleejordan

src/PowerShellEditorServices.Hosting/Commands/StartEditorServicesCommand.cs

@@ -12,12 +12,6 @@
 using System.Management.Automation.Runspaces;
 using Microsoft.PowerShell.EditorServices.Hosting;
 using System.Globalization;
-using System.Collections;
-
-// TODO: Remove this when we drop support for PS6.
-#if CoreCLR
-using System.Runtime.InteropServices;
-#endif
 
 #if DEBUG
 using System.Diagnostics;
@@ -35,14 +29,6 @@ namespace Microsoft.PowerShell.EditorServices.Commands
     [Cmdlet(VerbsLifecycle.Start, "EditorServices", DefaultParameterSetName = "NamedPipe")]
     public sealed class StartEditorServicesCommand : PSCmdlet
     {
-        // TODO: Remove this when we drop support for PS6.
-        private static readonly bool s_isWindows =
-#if CoreCLR
-        RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
-#else
-        true;
-#endif
-
         private readonly List<IDisposable> _disposableResources;
 
         private readonly List<IDisposable> _loggerUnsubscribers;
@@ -420,12 +406,7 @@ private ConsoleReplKind GetReplKind()
                 return ConsoleReplKind.None;
             }
 
-            // TODO: Remove this when we drop support for PS6.
-            Hashtable psVersionTable = (Hashtable)SessionState.PSVariable.GetValue("PSVersionTable");
-            dynamic version = psVersionTable["PSVersion"];
-            int majorVersion = (int)version.Major;
-
-            if (UseLegacyReadLine || (!s_isWindows && majorVersion == 6))
+            if (UseLegacyReadLine)
             {
                 _logger.Log(PsesLogLevel.Diagnostic, "REPL configured as Legacy");
                 return ConsoleReplKind.LegacyReadLine;