Fetch, XHR: Use ", " as header list value separator.

third_party/WebKit/Source/modules/fetch/FetchHeaderList.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/fetch/FetchHeaderList.h"
 
 #include <algorithm>
 #include <utility>
 #include "platform/loader/fetch/FetchUtils.h"
 #include "platform/network/HTTPParsers.h"
@@ skipping 81 matching lines @@
   // 2. Otherwise, append a new header whose name is |name| and value is
   //    |value| to |list|."
   StringBuilder resultBuilder;
   bool found = false;
   auto range = header_list_.equal_range(name);
   for (auto header = range.first; header != range.second; ++header) {
     if (!found) {
       resultBuilder.Append(header->second);
       found = true;
     } else {
-      // TODO(rakuco): This must be ", " instead. crbug.com/700434.
-      resultBuilder.Append(',');
+      resultBuilder.Append(", ");
       resultBuilder.Append(header->second);
     }
   }
   if (found)
     result = resultBuilder.ToString();
   return found;
 }
 
 // This is going to be removed: see crbug.com/645492.
 void FetchHeaderList::GetAll(const String& name, Vector<String>& result) const {
@@ skipping 52 matching lines @@
   return IsValidHTTPToken(name);
 }
 
 bool FetchHeaderList::IsValidHeaderValue(const String& value) {
   // "A value is a byte sequence that matches the field-value token production
   // and contains no 0x0A or 0x0D bytes."
   return IsValidHTTPHeaderValue(value);
 }
 
 }  // namespace blink