Add `Model` assessor to `ViewResult` for MVC5 portability.

#3495

src/Microsoft.AspNet.Mvc.ViewFeatures/ViewResult.cs

@@ -28,6 +28,11 @@ namespace Microsoft.AspNet.Mvc
         /// </remarks>
         public string ViewName { get; set; }
 
+        /// <summary>
+        /// Gets the view data model.
+        /// </summary>
+        public object Model => ViewData?.Model;
+
         /// <summary>
         /// Gets or sets the <see cref="ViewDataDictionary"/> for this result.
         /// </summary>

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/ViewResultTest.cs

@@ -24,6 +24,33 @@ namespace Microsoft.AspNet.Mvc
     // and ViewExecutorTest for more comprehensive tests.
     public class ViewResultTest
     {
+        [Fact]
+        public void Model_NullWhenViewDataIsNull()
+        {
+            // Arrange
+            var viewResult = new ViewResult();
+
+            // Act & Assert
+            Assert.Null(viewResult.Model);
+        }
+
+        [Fact]
+        public void Model_ExposesViewDataModel()
+        {
+            // Arrange
+            var customModel = new object();
+            var viewResult = new ViewResult
+            {
+                ViewData = new ViewDataDictionary(new EmptyModelMetadataProvider())
+                {
+                    Model = customModel
+                },
+            };
+
+            // Act & Assert
+            Assert.Same(customModel, viewResult.Model);
+        }
+
         [Fact]
         public async Task ExecuteResultAsync_Throws_IfViewCouldNotBeFound_MessageUsesGetViewLocations()
         {