Imported Upstream version 3.6.0

Former-commit-id: da6be194a6b1221998fc28233f2503bd61dd9d14

external/aspnetwebstack/src/System.Web.Razor/Text/ITextBuffer.cs

@@ -0,0 +1,18 @@
+// Copyright (c) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.
+
+namespace System.Web.Razor.Text
+{
+    public interface ITextBuffer
+    {
+        int Length { get; }
+        int Position { get; set; }
+        int Read();
+        int Peek();
+    }
+
+    // TextBuffer with Location tracking
+    public interface ITextDocument : ITextBuffer
+    {
+        SourceLocation Location { get; }
+    }
+}