feat(Animated): Adds support for DiffClamp node

Add support for DiffClamp node on Windows for `Animated.diffClamp` that was added in facebook/react-native#9419.

ReactWindows/ReactNative/Animated/DiffClampAnimatedNode.cs

@@ -0,0 +1,46 @@
+using Newtonsoft.Json.Linq;
+using System;
+
+namespace ReactNative.Animated
+{
+    class DiffClampAnimatedNode : ValueAnimatedNode
+    {
+        private readonly NativeAnimatedNodesManager _nativeAnimatedNodesManager;
+        private readonly int _inputNodeTag;
+        private readonly double _min;
+        private readonly double _max;
+
+        private double _lastValue;
+
+        public DiffClampAnimatedNode(int tag, JObject config, NativeAnimatedNodesManager nativeAnimatedNodesManager) 
+            : base(tag, config)
+        {
+            _nativeAnimatedNodesManager = nativeAnimatedNodesManager;
+            _inputNodeTag = config.Value<int>("input");
+            _min = config.Value<double>("min");
+            _max = config.Value<double>("max");
+
+            Value = _lastValue = GetInputNodeValue();
+        }
+
+        public override void Update()
+        {
+            var value = GetInputNodeValue();
+
+            var diff = value - _lastValue;
+            _lastValue = value;
+            Value = Math.Min(Math.Max(Value + diff, _min), _max);
+        }
+
+        private double GetInputNodeValue()
+        {
+            var valueAnimatedNode = _nativeAnimatedNodesManager.GetNodeById(_inputNodeTag) as ValueAnimatedNode;
+            if (valueAnimatedNode == null) {
+                throw new InvalidOperationException(
+                    "Illegal node ID set as an input for Animated.DiffClamp node.");
+            }
+
+            return valueAnimatedNode.Value;
+        }
+    }
+}

ReactWindows/ReactNative/Animated/NativeAnimatedNodesManager.cs

@@ -77,6 +77,9 @@ public void CreateAnimatedNode(int tag, JObject config)
                 case "multiplication":
                     node = new MultiplicationAnimatedNode(tag, config, this);
                     break;
+                case "diffclamp":
+                    node = new DiffClampAnimatedNode(tag, config, this);
+                    break;
                 case "transform":
                     node = new TransformAnimatedNode(tag, config, this);
                     break;

ReactWindows/ReactNative/ReactNative.csproj

@@ -95,6 +95,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="Animated\AdditionAnimatedNode.cs" />
+    <Compile Include="Animated\DiffClampAnimatedNode.cs" />
     <Compile Include="Animated\MultiplicationAnimatedNode.cs" />
     <Compile Include="Animated\NativeAnimatedModule.cs" />
     <Compile Include="Animated\NativeAnimatedNodesManager.cs" />