Add a few more [Obsolete] tags in things that are indeed Obsolete

src/VisualStudio/Core/Def/Implementation/ProjectSystem/AbstractProject.cs

@@ -2,20 +2,14 @@
 
 using System;
 using System.Collections.Immutable;
-using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Diagnostics;
-using Microsoft.CodeAnalysis.Editor.Shared.Options;
 using Microsoft.CodeAnalysis.Editor.Shared.Utilities;
-using Microsoft.CodeAnalysis.ErrorReporting;
 using Microsoft.CodeAnalysis.Host;
-using Microsoft.CodeAnalysis.Internal.Log;
-using Microsoft.CodeAnalysis.PooledObjects;
 using Microsoft.CodeAnalysis.Text;
 using Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel;
-using Microsoft.VisualStudio.LanguageServices.Implementation.EditAndContinue;
 using Microsoft.VisualStudio.LanguageServices.Implementation.TaskList;
 using Microsoft.VisualStudio.LanguageServices.Implementation.Venus;
 using Microsoft.VisualStudio.Shell.Interop;
@@ -26,10 +20,8 @@ namespace Microsoft.VisualStudio.LanguageServices.Implementation.ProjectSystem
 {
     using Workspace = Microsoft.CodeAnalysis.Workspace;
 
-    // NOTE: Microsoft.VisualStudio.LanguageServices.TypeScript.TypeScriptProject derives from AbstractProject.
-#pragma warning disable CS0618 // IVisualStudioHostProject is obsolete
+    [Obsolete("This is a compatibility shim for TypeScript and Live Unit Testing; please do not use it.")]
     internal abstract partial class AbstractProject : ForegroundThreadAffinitizedObject, IVisualStudioHostProject
-#pragma warning restore CS0618 // IVisualStudioHostProject is obsolete
     {
         internal const string ProjectGuidPropertyName = "ProjectGuid";
 

src/VisualStudio/Core/Def/Implementation/ProjectSystem/VisualStudioProjectTracker.cs

@@ -114,6 +114,7 @@ public AbstractProject GetProject(ProjectId projectId)
             }
         }
 
+        [Obsolete("This is a compatibility shim for TypeScript and F#; please do not use it.")]
         internal bool TryGetProjectByBinPath(string filePath, out AbstractProject project)
         {
             var projectsWithBinPath = _workspace.CurrentSolution.Projects.Where(p => string.Equals(p.OutputFilePath, filePath, StringComparison.OrdinalIgnoreCase)).ToList();
@@ -130,6 +131,7 @@ internal bool TryGetProjectByBinPath(string filePath, out AbstractProject projec
             }
         }
 
+        [Obsolete("This is a compatibility shim for TypeScript and F#; please do not use it.")]
         private sealed class StubProject : AbstractProject
         {
             private readonly ProjectId _id;

src/VisualStudio/Core/Def/Implementation/ProjectSystem/VisualStudioWorkspaceImpl.cs

@@ -246,6 +246,7 @@ internal override string TryGetRuleSetPathForProject(ProjectId projectId)
             }
         }
 
+        [Obsolete("This is a compatibility shim for Live Unit Testing; please do not use it.")]
         private sealed class StubProject : AbstractProject
         {
             private readonly string _outputPath;