Save 8/4 bytes per node instance

Author: alex-kulakov

Orm/Xtensive.Orm/Sql/Compiler/Internals/Nodes/ContainerNode.cs

@@ -153,7 +153,7 @@ public void Add(Node node)
     {
       FlushBuffer();
       children.Add(node);
-      lastNodeIsText = node.IsTextNode;
+      lastNodeIsText = node is TextNode;
     }
 
     internal override void AcceptVisitor(NodeVisitor visitor)

Orm/Xtensive.Orm/Sql/Compiler/Internals/Nodes/Node.cs

@@ -9,17 +9,6 @@ namespace Xtensive.Sql.Compiler
   /// </summary>
   public abstract class Node
   {
-    internal readonly bool IsTextNode;
-
     internal abstract void AcceptVisitor(NodeVisitor visitor);
-
-    public Node()
-    {
-    }
-
-    internal Node(bool isTextNode)
-    {
-      IsTextNode = isTextNode;
-    }
   }
-}
+}

Orm/Xtensive.Orm/Sql/Compiler/Internals/Nodes/TextNode.cs

@@ -29,8 +29,7 @@ public static TextNode Create(string text)
 
     // Constructor
 
-    private TextNode(string text)
-      : base(true)
+    public TextNode(string text)
     {
       Text = text;
     }