Delete FriendAccessAllowedAttribute and associated dead code (#15101)

- Preserved commented out FriendAccessAllowed on types and methods that are still used as friends in System.Runtime.WindowsRuntime

Signed-off-by: dotnet-bot-corefx-mirror <dotnet-bot@microsoft.com>

Author: jkotas

src/Common/src/CoreLib/System/Diagnostics/Tracing/Winmeta.cs

@@ -55,9 +55,6 @@ public enum EventLevel
     /// <summary>
     /// WindowsEventTask. Custom values must be in the range from 1 through 65534
     /// </summary>
-#if (!ES_BUILD_STANDALONE && !ES_BUILD_PN)
-    [System.Runtime.CompilerServices.FriendAccessAllowed]
-#endif
     public enum EventTask
     {
         /// <summary>
@@ -68,9 +65,6 @@ public enum EventTask
     /// <summary>
     /// EventOpcode. Custom values must be in the range from 11 through 239
     /// </summary>
-#if (!ES_BUILD_STANDALONE && !ES_BUILD_PN)
-    [System.Runtime.CompilerServices.FriendAccessAllowed]
-#endif
     public enum EventOpcode
     {
         /// <summary>
@@ -124,9 +118,6 @@ public enum EventOpcode
     /// EventChannel. Custom values must be in the range from 16 through 255. Currently only predefined values allowed.
     /// </summary>
     [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1028:EnumStorageShouldBeInt32", Justification = "Backwards compatibility")]
-#if (!ES_BUILD_STANDALONE && !ES_BUILD_PN)
-    [System.Runtime.CompilerServices.FriendAccessAllowed]
-#endif
     public enum EventChannel : byte
     {
         /// <summary>

src/Common/src/CoreLib/System/ObjectDisposedException.cs

@@ -72,7 +72,7 @@ public String ObjectName
         {
             get
             {
-                if ((_objectName == null)) // && !CompatibilitySwitches.IsAppEarlierThanWindowsPhone8)
+                if (_objectName == null)
                 {
                     return String.Empty;
                 }