Addressed code review comments.

Author: NTaylorMullen

src/Microsoft.AspNet.Mvc.TagHelpers/AnchorTagHelper.cs

@@ -57,24 +57,25 @@ public class AnchorTagHelper : TagHelper
         public string Route { get; set; }
 
         /// <inheritdoc />
-        /// <remarks>Does nothing if user provides an "href" attribute. Cannot specify an "href" attribute AND 
-        /// <see cref="Action"/>, <see cref="Controller"/> or <see cref="Route"/>.</remarks>
+        /// <remarks>Does nothing if user provides an "href" attribute. Providing an "href" attribute and 
+        /// <see cref="Action"/>, <see cref="Controller"/> or <see cref="Route"/> throws an
+        /// <see cref="InvalidOperationException"/>.</remarks>
         public override void Process(TagHelperContext context, TagHelperOutput output)
         {
-            var routeValues = GetRouteValues(output);
+            var routePrefixedAttributes = output.FindPrefixedAttributes(RouteAttributePrefix);
 
             // If there's an "href" on the tag it means it's being used as a normal anchor.
             if (output.Attributes.ContainsKey(Href))
             {
-                if (Action != null || Controller != null || Route != null || routeValues != null)
+                if (Action != null || Controller != null || Route != null || routePrefixedAttributes.Any())
                 {
                     // User specified an href AND a Action, Controller or Route; can't determine the href attribute.
                     throw new InvalidOperationException(
-                        Resources.FormatAnchorTagHelper_CannotDetermineHrefOneSpecified(
+                        Resources.FormatAnchorTagHelper_CannotOverrideSpecifiedHref(
                             "<a>",
-                            nameof(Action),
-                            nameof(Controller),
-                            nameof(Route),
+                            nameof(Action).ToLowerInvariant(),
+                            nameof(Controller).ToLowerInvariant(),
+                            nameof(Route).ToLowerInvariant(),
                             RouteAttributePrefix,
                             Href));
                 }
@@ -85,6 +86,7 @@ public override void Process(TagHelperContext context, TagHelperOutput output)
             else
             {
                 TagBuilder tagBuilder;
+                var routeValues = GetRouteValues(output, routePrefixedAttributes);
 
                 if (Route == null)
                 {
@@ -103,9 +105,9 @@ public override void Process(TagHelperContext context, TagHelperOutput output)
                     throw new InvalidOperationException(
                         Resources.FormatAnchorTagHelper_CannotDetermineHrefRouteActionOrControllerSpecified(
                             "<a>",
-                            nameof(Route),
-                            nameof(Action),
-                            nameof(Controller),
+                            nameof(Route).ToLowerInvariant(),
+                            nameof(Action).ToLowerInvariant(),
+                            nameof(Controller).ToLowerInvariant(),
                             Href));
                 }
                 else
@@ -126,41 +128,41 @@ public override void Process(TagHelperContext context, TagHelperOutput output)
             }
         }
 
-        private static Dictionary<string, object> GetRouteValues(TagHelperOutput output)
+        // TODO: We will not need this method once https://github.com/aspnet/Razor/issues/89 is completed.
+        private static Dictionary<string, object> GetRouteValues(
+            TagHelperOutput output, IEnumerable<KeyValuePair<string, string>> routePrefixedAttributes)
         {
-            var prefixedValues = output.PullPrefixedAttributes(RouteAttributePrefix);
-
             Dictionary<string, object> routeValues = null;
-
-            if (prefixedValues.Any())
+            if (routePrefixedAttributes.Any())
             {
-                // Generator.GenerateActionLink || GenerateRouteLink does not accept a Dictionary<string, string> for
-                // route values.
-                routeValues = prefixedValues.ToDictionary(
+                // Prefixed values should be treated as bound attributes, remove them from the output.
+                output.RemoveRange(routePrefixedAttributes);
+
+                // Generator.GenerateForm does not accept a Dictionary<string, string> for route values.
+                routeValues = routePrefixedAttributes.ToDictionary(
                     attribute => attribute.Key.Substring(RouteAttributePrefix.Length),
                     attribute => (object)attribute.Value);
             }
 
             return routeValues;
         }
 
-
         // Restores bound HTML attributes when we detect that a user is using the AnchorTagHelper as a normal <a> tag.
         private void RestoreBoundHtmlAttributes(TagHelperContext context, TagHelperOutput output)
         {
             if (Protocol != null)
             {
-                output.RestoreBoundHtmlAttribute(nameof(Protocol), context);
+                output.CopyHtmlAttribute(nameof(Protocol), context);
             }
 
             if (Host != null)
             {
-                output.RestoreBoundHtmlAttribute(nameof(Host), context);
+                output.CopyHtmlAttribute(nameof(Host), context);
             }
 
             if (Fragment != null)
             {
-                output.RestoreBoundHtmlAttribute(nameof(Fragment), context);
+                output.CopyHtmlAttribute(nameof(Fragment), context);
             }
         }
     }

src/Microsoft.AspNet.Mvc.TagHelpers/Properties/Resources.Designer.cs

@@ -117,12 +117,12 @@
   <resheader name="writer">
     <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
-  <data name="AnchorTagHelper_CannotDetermineHrefOneSpecified" xml:space="preserve">
-    <value>Cannot determine an {5} for {0}. An {0} with a specified {5} must not have attributes starting with {4} or a {1}, {2} or {3} attribute.</value>
-  </data>
   <data name="AnchorTagHelper_CannotDetermineHrefRouteActionOrControllerSpecified" xml:space="preserve">
     <value>Cannot determine an {4} for {0}. An {0} with a specified {1} must not have a {2} or {3} attribute.</value>
   </data>
+  <data name="AnchorTagHelper_CannotOverrideSpecifiedHref" xml:space="preserve">
+    <value>Cannot determine an {5} for {0}. An {0} with a specified {5} must not have attributes starting with {4} or a {1}, {2} or {3} attribute.</value>
+  </data>
   <data name="FormTagHelper_CannotDetermineAction" xml:space="preserve">
     <value>Cannot determine an {1} for {0}. A {0} with a URL-based {1} must not have attributes starting with {3} or a {2} attribute.</value>
   </data>

src/Microsoft.AspNet.Mvc.TagHelpers/Resources.resx

@@ -217,7 +217,7 @@ public async Task ProcessAsync_ThrowsIfHrefConflictsWithBoundAttributes(string p
             }
 
             var expectedErrorMessage = "Cannot determine an href for <a>. An <a> with a specified href must not " +
-                                       "have attributes starting with route- or a Action, Controller or Route " +
+                                       "have attributes starting with route- or a action, controller or route " +
                                        "attribute.";
 
             // Act & Assert
@@ -246,7 +246,7 @@ public async Task ProcessAsync_ThrowsIfRouteAndActionOrControllerProvided(string
                 attributes: new Dictionary<string, string>(),
                 content: string.Empty);
             var expectedErrorMessage = "Cannot determine an href for <a>. An <a> with a " +
-                                       "specified Route must not have a Action or Controller attribute.";
+                                       "specified route must not have a action or controller attribute.";
 
             // Act & Assert
             var ex = await Assert.ThrowsAsync<InvalidOperationException>(