InputSize simplification

Web/Views/Shared/EditorTemplates/DateTime.cshtml

@@ -1,17 +1,12 @@
-@model DateTime?
+@using MileageTraker.Web.Utility
+@model DateTime?
 @{
     Layout = "~/Views/Shared/EditorTemplates/_FieldLayout.cshtml";
-    var inputSize = (string)ViewData.ModelMetadata.AdditionalValues["InputSize"];
 	var val =
 		Model.HasValue
 		? Model.Value.ToShortDateString()
 		: string.Empty;
 }
-@if (!string.IsNullOrEmpty(inputSize))
-{
-    @Html.TextBox("", (Model != DateTime.MinValue ? val : string.Empty ), new { @class = inputSize})
-}
-else
-{
-    @Html.TextBox("", (Model != DateTime.MinValue ? val : string.Empty ))
-}
+
+@Html.TextBox("", (Model != DateTime.MinValue ? val : string.Empty ), Html.GetInputSizeClass())
+