Remove code.

src/Workspaces/Core/Portable/FindSymbols/SyntaxTree/SyntaxTreeIdentifierInfo_Set.cs

-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
-
-using System.Collections.Generic;
-using System.Threading;
-using System.Threading.Tasks;
-using Microsoft.CodeAnalysis.Host;
-using Microsoft.CodeAnalysis.Shared.Extensions;
-using Microsoft.CodeAnalysis.Versions;
-using Roslyn.Utilities;
-
-namespace Microsoft.CodeAnalysis.FindSymbols
-{
-    internal partial class SyntaxTreeIdentifierInfo
-    {
-        public static bool TryGetIdentifierLocations(Document document, VersionStamp version, string identifier, List<int> positions, CancellationToken cancellationToken)
-        {
-            var persistentStorageService = document.Project.Solution.Workspace.Services.GetService<IPersistentStorageService>();
-            using (var storage = persistentStorageService.GetStorage(document.Project.Solution))
-            {
-                var esentStorage = storage as ISyntaxTreeInfoPersistentStorage;
-                if (esentStorage == null)
-                {
-                    // basically, we don't support it. return true so that we don't try to precalculate it
-                    return false;
-                }
-
-                return esentStorage.ReadIdentifierPositions(document, version, identifier, positions, cancellationToken);
-            }
-        }
-
-        public static async Task<bool> IdentifierSetPrecalculatedAsync(Document document, CancellationToken cancellationToken)
-        {
-            var syntaxVersion = await document.GetSyntaxVersionAsync(cancellationToken).ConfigureAwait(false);
-            var persistentStorageService = document.Project.Solution.Workspace.Services.GetService<IPersistentStorageService>();
-
-            using (var storage = persistentStorageService.GetStorage(document.Project.Solution))
-            {
-                var esentStorage = storage as ISyntaxTreeInfoPersistentStorage;
-                if (esentStorage == null)
-                {
-                    // basically, we don't support it. return true so that we don't try to precalculate it
-                    return true;
-                }
-
-                var persistedVersion = esentStorage.GetIdentifierSetVersion(document);
-                return document.CanReusePersistedSyntaxTreeVersion(syntaxVersion, persistedVersion);
-            }
-        }
-
-        public static async Task SaveIdentifierSetAsync(Document document, CancellationToken cancellationToken)
-        {
-            Contract.Requires(document.IsFromPrimaryBranch());
-
-            var persistentStorageService = document.Project.Solution.Workspace.Services.GetService<IPersistentStorageService>();
-
-            using (var storage = persistentStorageService.GetStorage(document.Project.Solution))
-            {
-                var esentStorage = storage as ISyntaxTreeInfoPersistentStorage;
-                if (esentStorage == null)
-                {
-                    return;
-                }
-
-                var version = await document.GetSyntaxVersionAsync(cancellationToken).ConfigureAwait(false);
-                var root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
-
-                esentStorage.WriteIdentifierLocations(document, version, root, cancellationToken);
-            }
-        }
-    }
-}