Fixes #1308 and #1315

Misc project item cleanup

src/Microsoft.AspNetCore.Razor.Language/FileSystemRazorProjectItem.cs

@@ -28,8 +28,6 @@ namespace Microsoft.AspNetCore.Razor.Language
 
         public override bool Exists => File.Exists;
 
-        public override string FileName => File.Name;
-
         public override string PhysicalPath => File.FullName;
 
         public override Stream Read() => File.OpenRead();

src/Microsoft.AspNetCore.Razor.Language/NotFoundProjectItem.cs

@@ -9,7 +9,7 @@ namespace Microsoft.AspNetCore.Razor.Language
     /// <summary>
     /// A <see cref="RazorProjectItem"/> that does not exist.
     /// </summary>
-    public class NotFoundProjectItem : RazorProjectItem
+    internal class NotFoundProjectItem : RazorProjectItem
     {
         /// <summary>
         /// Initializes a new instance of <see cref="NotFoundProjectItem"/>.

src/Microsoft.AspNetCore.Razor.Language/RazorProjectItem.cs

@@ -41,7 +41,7 @@ namespace Microsoft.AspNetCore.Razor.Language
         /// <summary>
         /// The root relative path of the item.
         /// </summary>
-        public virtual string CombinedPath
+        public string CombinedPath
         {
             get
             {
@@ -59,7 +59,7 @@ namespace Microsoft.AspNetCore.Razor.Language
         /// <summary>
         /// The extension of the file.
         /// </summary>
-        public virtual string Extension
+        public string Extension
         {
             get
             {
@@ -78,7 +78,7 @@ namespace Microsoft.AspNetCore.Razor.Language
         /// <summary>
         /// The name of the file including the extension.
         /// </summary>
-        public virtual string FileName
+        public string FileName
         {
             get
             {
@@ -90,7 +90,7 @@ namespace Microsoft.AspNetCore.Razor.Language
         /// <summary>
         /// Path relative to <see cref="BasePath"/> without the extension.
         /// </summary>
-        public virtual string PathWithoutExtension
+        public string PathWithoutExtension
         {
             get
             {