we are no longer shipping MS.IO.Redist, there is no need for FileInfo…

… to be partial

src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems

@@ -417,7 +417,6 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\IO\FileAccess.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\IO\FileAttributes.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\IO\FileInfo.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\IO\FileInfo.netcoreapp.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\IO\FileLoadException.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\IO\FileMode.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\IO\FileNotFoundException.cs" />

src/libraries/System.Private.CoreLib/src/System/IO/FileInfo.cs

@@ -1,17 +1,15 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using System;
 using System.Diagnostics;
-using System.IO;
 using System.Text;
 using System.Runtime.Versioning;
 
 namespace System.IO
 {
     // Class for creating FileStream objects, and some basic file management
     // routines such as Delete, etc.
-    public sealed partial class FileInfo : FileSystemInfo
+    public sealed class FileInfo : FileSystemInfo
     {
         private FileInfo() { }
 
@@ -72,6 +70,12 @@ public bool IsReadOnly
             }
         }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="System.IO.FileStream" /> class with the specified creation mode, read/write and sharing permission, the access other FileStreams can have to the same file, the buffer size, additional file options and the allocation size.
+        /// </summary>
+        /// <remarks><see cref="System.IO.FileStream(string,System.IO.FileStreamOptions)"/> for information about exceptions.</remarks>
+        public FileStream Open(FileStreamOptions options) => File.Open(NormalizedPath, options);
+
         public StreamReader OpenText()
             => new StreamReader(NormalizedPath, Encoding.UTF8, detectEncodingFromByteOrderMarks: true);