Use the existing instance identifier constant in the CLI backend to match the C# generator.

src/Generator/Generators/CLI/CLIHeadersTemplate.cs

@@ -288,7 +288,7 @@ namespace CppSharp.Generators.CLI
             WriteLineIndent("property {0} NativePtr;", nativeType);
 
             PushIndent();
-            WriteLine("property System::IntPtr Instance");
+            WriteLine("property System::IntPtr {0}", Helpers.InstanceIdentifier);
             WriteStartBraceIndent();
             WriteLine("virtual System::IntPtr get();");
             WriteLine("virtual void set(System::IntPtr instance);");

src/Generator/Generators/CLI/CLISourcesTemplate.cs

@@ -152,16 +152,16 @@ namespace CppSharp.Generators.CLI
             if (CSharpTextTemplate.ShouldGenerateClassNativeField(@class))
             {
                 PushBlock(CLIBlockKind.Method);
-                WriteLine("System::IntPtr {0}::Instance::get()",
-                            QualifiedIdentifier(@class));
+                WriteLine("System::IntPtr {0}::{1}::get()",
+                    QualifiedIdentifier(@class), Helpers.InstanceIdentifier);
                 WriteStartBraceIndent();
                 WriteLine("return System::IntPtr(NativePtr);");
                 WriteCloseBraceIndent();
                 PopBlock(NewLineKind.BeforeNextBlock);
 
                 PushBlock(CLIBlockKind.Method);
-                WriteLine("void {0}::Instance::set(System::IntPtr object)",
-                            QualifiedIdentifier(@class));
+                WriteLine("void {0}::{1}::set(System::IntPtr object)",
+                    QualifiedIdentifier(@class), Helpers.InstanceIdentifier);
                 WriteStartBraceIndent();
                 var nativeType = string.Format("::{0}*", @class.QualifiedOriginalName);
                 WriteLine("NativePtr = ({0})object.ToPointer();", nativeType);