Add 'XHR' to the Resource::Type enum, and use it for XHR requests.

Source/core/fetch/Resource.h

Index: Source/core/fetch/Resource.h
diff --git a/Source/core/fetch/Resource.h b/Source/core/fetch/Resource.h
index 829cd67cc864df56b95811416d5042c0ab390bff..aab21a2addae39519e8a5376e14089cc4b0aa21a 100644
--- a/Source/core/fetch/Resource.h
+++ b/Source/core/fetch/Resource.h
@@ -71,7 +71,8 @@ public:
         LinkSubresource,
         TextTrack,
         ImportResource,
-        Media // Audio or video file requested by a HTML5 media element
+        Media, // Audio or video file requested by a HTML5 media element
+        XMLHttpRequest
     };
 
     enum Status {
@@ -154,6 +155,7 @@ public:
             || type() == LinkSubresource
             || type() == Media
             || type() == Raw
+            || type() == XMLHttpRequest
             || type() == TextTrack;
     }