Ensure we can set double properties with ints.

Tests/Perspex.Base.UnitTests/PerspexObjectTests.cs

@@ -171,6 +171,14 @@ namespace Perspex.Base.UnitTests
             });
         }
 
+        [Fact]
+        public void SetValue_Of_Integer_On_Double_Property_Works()
+        {
+            Class2 target = new Class2();
+
+            target.SetValue(Class2.FlobProperty, 4);
+        }
+
         [Fact]
         public void SetValue_Causes_Coercion()
         {
@@ -615,6 +623,9 @@ namespace Perspex.Base.UnitTests
             public static readonly PerspexProperty<string> BarProperty =
                 PerspexProperty.Register<Class2, string>("Bar", "bardefault");
 
+            public static readonly PerspexProperty<double> FlobProperty =
+                PerspexProperty.Register<Class2, double>("Flob");
+
             static Class2()
             {
                 FooProperty.OverrideDefaultValue(typeof(Class2), "foooverride");