C# transpiler, API, and tests

src/csharp/Facebook.CSSLayout/CSSConstants.cs

@@ -0,0 +1,21 @@
+/**
+ * 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.
+ */
+
+namespace Facebook.CSSLayout
+{
+    public static class CSSConstants 
+    {
+        public static readonly float Undefined = float.NaN;
+
+        public static bool IsUndefined(float value) 
+        {
+            return float.IsNaN(value);
+        }
+    }
+}