Never use the XML as parsed by the XHR instance. Use raw text instead and let...

Never use the XML as parsed by the XHR instance. Use raw text instead and let the ajax conversion logic do the trick. -20 min/gzipped. Fixes #13276. Unit test added.

src/ajax/xhr.js

@@ -105,8 +105,7 @@ if ( xhrSupported ) {
 						var status,
 							statusText,
 							responseHeaders,
-							responses,
-							xml;
+							responses;
 
 						// Firefox throws exceptions when accessing properties
 						// of an xhr when a network error occurred
@@ -136,14 +135,8 @@ if ( xhrSupported ) {
 								} else {
 									responses = {};
 									status = xhr.status;
-									xml = xhr.responseXML;
 									responseHeaders = xhr.getAllResponseHeaders();
 
-									// Construct response list
-									if ( xml && xml.documentElement /* #4958 */ ) {
-										responses.xml = xml;
-									}
-
 									// When requesting binary data, IE6-9 will throw an exception
 									// on any attempt to access responseText (#11426)
 									if ( typeof xhr.responseText === "string" ) {

test/unit/ajax.js

@@ -1483,6 +1483,22 @@ module( "ajax", {
 		
 	});
 
+	ajaxTest( "#13276 - jQuery.ajax() - compatibility between XML documents from ajax requests and parsed string", 1, {
+		url: "data/dashboard.xml",
+		dataType: "xml",
+		success: function( ajaxXML ) {
+			var parsedXML = jQuery( jQuery.parseXML("<tab title=\"Added\">blibli</tab>") ).find("tab");
+			ajaxXML = jQuery( ajaxXML );
+			try {
+				ajaxXML.find("infowindowtab").append( parsedXML );
+			} catch( e ) {
+				strictEqual( e, undefined, "error" );
+				return;
+			}
+			strictEqual( ajaxXML.find("tab").length, 3, "Parsed node was added properly" );
+		}
+	});
+
 //----------- jQuery.ajaxPrefilter()
 
 	ajaxTest( "jQuery.ajaxPrefilter() - abort", 1, {