ProfilingList: make a DEBUG-only CheckCapacity() function

Shared/ProfilingList.cs

@@ -1,13 +1,14 @@
 using System.Collections;
 using System.Collections.Generic;
+using System.Diagnostics;
 
 namespace SemiColinGames {
   // An IList<T>, backed by a List<T>, that prints out a debug message any time that the Capacity
   // of the underlying List changes.
   public class ProfilingList<T> : IList<T> {
-    private List<T> items;
+    private readonly List<T> items;
+    private readonly string name;
     private int previousCapacity;
-    private string name;
 
     public ProfilingList(int capacity, string name) {
       items = new List<T>(capacity);
@@ -15,26 +16,28 @@ namespace SemiColinGames {
       this.name = name;
     }
 
+    public bool IsReadOnly {
+      get { return false; }
+    }
+
     public void Add(T item) {
       items.Add(item);
-      if (items.Capacity != previousCapacity) {
-        Debug.WriteLine($"{name} capacity: {previousCapacity} -> {items.Capacity}");
-        previousCapacity = items.Capacity;
-      }
+      CheckCapacity();
     }
 
     public void Insert(int index, T item) {
       items.Insert(index, item);
+      CheckCapacity();
+    }
+
+    [Conditional("DEBUG")]
+    private void CheckCapacity() {
       if (items.Capacity != previousCapacity) {
         Debug.WriteLine($"{name} capacity: {previousCapacity} -> {items.Capacity}");
         previousCapacity = items.Capacity;
       }
     }
 
-    public bool IsReadOnly {
-      get { return false; }
-    }
-
     // Everything below this point is boilerplate delegation to the underlying list.
 
     public void Clear() {