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

Source/core/fetch/RawResource.h

Index: Source/core/fetch/RawResource.h
diff --git a/Source/core/fetch/RawResource.h b/Source/core/fetch/RawResource.h
index 10bae27deb1cbcf65d9949ae52278bc84253e136..85ab30a284e1a630e020f4256f320476f3362214 100644
--- a/Source/core/fetch/RawResource.h
+++ b/Source/core/fetch/RawResource.h
@@ -60,7 +60,7 @@ private:
 inline bool isRawResource(const Resource& resource)
 {
     Resource::Type type = resource.type();
-    return type == Resource::MainResource || type == Resource::Raw || type == Resource::TextTrack || type == Resource::Media || type == Resource::ImportResource;
+    return type == Resource::MainResource || type == Resource::Raw || type == Resource::TextTrack || type == Resource::Media || type == Resource::ImportResource || type == Resource::XMLHttpRequest;
 }
 #endif
 inline RawResource* toRawResource(const ResourcePtr<Resource>& resource)