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

Source/core/xml/XMLHttpRequest.cpp

Index: Source/core/xml/XMLHttpRequest.cpp
diff --git a/Source/core/xml/XMLHttpRequest.cpp b/Source/core/xml/XMLHttpRequest.cpp
index f5bb0de78ec338577cccb188fcaa8afb27d887dc..b7bd5a249896d7aea89f06579d904147879a8e2a 100644
--- a/Source/core/xml/XMLHttpRequest.cpp
+++ b/Source/core/xml/XMLHttpRequest.cpp
@@ -861,7 +861,7 @@ void XMLHttpRequest::createRequest(PassRefPtr<FormData> httpBody, ExceptionState
     resourceLoaderOptions.allowCredentials = (m_sameOriginRequest || m_includeCredentials) ? AllowStoredCredentials : DoNotAllowStoredCredentials;
     resourceLoaderOptions.credentialsRequested = m_includeCredentials ? ClientRequestedCredentials : ClientDidNotRequestCredentials;
     resourceLoaderOptions.securityOrigin = securityOrigin();
-    resourceLoaderOptions.mixedContentBlockingTreatment = TreatAsActiveContent;
+
 
     // When responseType is set to "blob", we redirect the downloaded data to a
     // file-handle directly.