Update XHR spec references in tests to HTTPS

third_party/WebKit/LayoutTests/http/tests/inspector/resource-har-conversion-expected.txt

-CONSOLE WARNING: Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience. For more help, check http://xhr.spec.whatwg.org/.
+CONSOLE WARNING: Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience. For more help, check https://xhr.spec.whatwg.org/.
 Tests conversion of Inspector's resource representation into HAR format.
 
 Page reloaded.
 {
     creator : {
         name : "WebInspector"
         version : <string>
     }
     entries : [
         {
@@ skipping 211 matching lines @@
                 onContentLoad : <number>
                 onLoad : <number>
             }
             startedDateTime : <plausible>
             title : "http://127.0.0.1:8000/inspector/resource-har-conversion.html"
         }
     ]
     version : <string>
 }