Introduce CSSAssertSetFailFunc and CSSAsserFail to throw managed exception

Summary:
- Define CSS_ASSERT_FAIL_ENABLED for P/Invoke (Visual Studio project already has it)
- Pass managed delegate pointer to unmanaged side via P/Invoke.
- CSSAssertFail will call the managed delegate when assert failed.
- The delegate will throw managed exception.

Reviewed By: emilsjolander

Differential Revision: D3982084

fbshipit-source-id: 058a87c10ca89238362be4d8759cc00dd0c9b376

tests/csharp/Facebook.CSSLayout/CSSNodeTest.cs

@@ -41,6 +41,21 @@ namespace Facebook.CSSLayout
             Assert.AreEqual(0, parent.Count);
         }
 
+        [Test]
+        [ExpectedException("System.InvalidOperationException")]
+        public void TestCannotAddChildToMultipleParents()
+        {
+            CSSNode parent1 = new CSSNode();
+            parent1.Initialize();
+            CSSNode parent2 = new CSSNode();
+            parent2.Initialize();
+            CSSNode child = new CSSNode();
+            child.Initialize();
+
+            parent1.Insert(0, child);
+            parent2.Insert(0, child);
+        }
+
         [Test]
         [ExpectedException("System.InvalidOperationException")]
         public void TestAlreadyInitialize()