Add Multiple attribute same name understanding to TagHelperChunk.

- This also involved adding understanding to CSharpTagHelperCodeRenderer.
- When rebasing this commit was lost as part of: 7c604d2b11 .

#279

src/Microsoft.AspNet.Razor/Generator/Compiler/CodeBuilder/CSharp/CSharpTagHelperCodeRenderer.cs

@@ -61,7 +61,7 @@ namespace Microsoft.AspNet.Razor.Generator.Compiler.CSharp
         public void RenderTagHelper(TagHelperChunk chunk)
         {
             // Remove any duplicate TagHelperDescriptors that reference the same type name. Duplicates can occur when
-            // multiple TargetElement attributes are on a TagHelper type and matchs overlap for an HTML element.
+            // multiple TargetElement attributes are on a TagHelper type and matches overlap for an HTML element.
             // Having more than one descriptor with the same TagHelper type results in generated code that runs
             // the same TagHelper X many times (instead of once) over a single HTML element.
             var tagHelperDescriptors = chunk.Descriptors.Distinct(TypeNameTagHelperDescriptorComparer.Default);
@@ -190,20 +190,21 @@ namespace Microsoft.AspNet.Razor.Generator.Compiler.CSharp
             }
         }
 
-        private void RenderBoundHTMLAttributes(IDictionary<string, Chunk> chunkAttributes,
+        private void RenderBoundHTMLAttributes(IList<KeyValuePair<string, Chunk>> chunkAttributes,
                                                string tagHelperVariableName,
                                                IEnumerable<TagHelperAttributeDescriptor> attributeDescriptors,
                                                Dictionary<string, string> htmlAttributeValues)
         {
             foreach (var attributeDescriptor in attributeDescriptors)
             {
-                Chunk attributeValueChunk;
+                var matchingAttributes = chunkAttributes.Where(
+                    attr => string.Equals(attr.Key, attributeDescriptor.Name, StringComparison.OrdinalIgnoreCase));
 
-                var providedAttribute = chunkAttributes.TryGetValue(attributeDescriptor.Name,
-                                                                    out attributeValueChunk);
-
-                if (providedAttribute)
+                if (matchingAttributes.Any())
                 {
+                    // First attribute wins, even if there's duplicates.
+                    var attributeValueChunk = matchingAttributes.First().Value;
+
                     var attributeValueRecorded = htmlAttributeValues.ContainsKey(attributeDescriptor.Name);
 
                     // Bufferable attributes are attributes that can have Razor code inside of them.

src/Microsoft.AspNet.Razor/Generator/Compiler/CodeTree/Chunks/TagHelpers/TagHelperChunk.cs

@@ -25,7 +25,7 @@ namespace Microsoft.AspNet.Razor.Generator.Compiler
         public TagHelperChunk(
             string tagName,
             bool selfClosing,
-            IDictionary<string, Chunk> attributes,
+            IList<KeyValuePair<string, Chunk>> attributes,
             IEnumerable<TagHelperDescriptor> descriptors)
         {
             TagName = tagName;
@@ -41,7 +41,7 @@ namespace Microsoft.AspNet.Razor.Generator.Compiler
         /// These attributes are <see cref="string"/> => <see cref="Chunk"/> so attribute values can consist
         /// of all sorts of Razor specific pieces.
         /// </remarks>
-        public IDictionary<string, Chunk> Attributes { get; set; }
+        public IList<KeyValuePair<string, Chunk>> Attributes { get; set; }
 
         /// <summary>
         /// The <see cref="TagHelperDescriptor"/>s that are associated with the tag helpers HTML element.

src/Microsoft.AspNet.Razor/Generator/TagHelperCodeGenerator.cs

@@ -47,7 +47,7 @@ namespace Microsoft.AspNet.Razor.Generator
                     RazorResources.TagHelpers_TagHelperCodeGeneartorMustBeAssociatedWithATagHelperBlock);
             }
 
-            var attributes = new Dictionary<string, Chunk>(StringComparer.OrdinalIgnoreCase);
+            var attributes = new List<KeyValuePair<string, Chunk>>();
 
             // We need to create a code generator to create chunks for each of the attributes.
             var codeGenerator = context.Host.CreateCodeGenerator(
@@ -63,12 +63,13 @@ namespace Microsoft.AspNet.Razor.Generator
                 var chunks = codeGenerator.Context.CodeTreeBuilder.CodeTree.Chunks;
                 var first = chunks.FirstOrDefault();
 
-                attributes[attribute.Key] = new ChunkBlock
-                {
-                    Association = first?.Association,
-                    Children = chunks,
-                    Start = first == null ? SourceLocation.Zero : first.Start
-                };
+                attributes.Add(new KeyValuePair<string, Chunk>(attribute.Key,
+                    new ChunkBlock
+                    {
+                        Association = first?.Association,
+                        Children = chunks,
+                        Start = first == null ? SourceLocation.Zero : first.Start
+                    }));
 
                 // Reset the code tree builder so we can build a new one for the next attribute
                 codeGenerator.Context.CodeTreeBuilder = new CodeTreeBuilder();

test/Microsoft.AspNet.Razor.Test/Generator/CSharpTagHelperRenderingUnitTest.cs

@@ -133,7 +133,7 @@ namespace Microsoft.AspNet.Razor.Test.Generator
             return new TagHelperChunk(
                 tagName,
                 selfClosing: false,
-                attributes: new Dictionary<string, Chunk>(),
+                attributes: new List<KeyValuePair<string, Chunk>>(),
                 descriptors: tagHelperDescriptors)
             {
                 Children = new List<Chunk>(),