Restructure things to fit upcoming diff

java/csharp/Facebook.CSSLayout/Assertions.cs

@@ -0,0 +1,27 @@
+/**
+ * Copyright (c) 2014, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+using System.Diagnostics;
+
+namespace Facebook.CSSLayout
+{
+    static class Assertions
+    {
+        public static T assertNotNull<T>(T v) where T : class
+        {
+            Debug.Assert(v != null);
+            return v;
+        }
+
+        public static void assertCondition(bool condition, string explanation)
+        {
+            Debug.Assert(condition, explanation);
+        }
+    }
+}