mshtml/tests: Allow ParseUrl to clear buffer on Win10.

dlls/mshtml/tests/protocol.c

@@ -720,7 +720,9 @@ static void test_about_protocol(void)
         hres = IInternetProtocolInfo_ParseUrl(protocol_info, about_blank_url, PARSE_DOMAIN, 0, buf,
                 sizeof(buf)/sizeof(buf[0]), &size, 0);
         ok(hres == S_OK || hres == E_FAIL, "ParseUrl failed: %08x\n", hres);
-        ok(buf[0] == '?', "buf changed\n");
+        ok(buf[0] == '?' || buf[0] == '\0' /* Win10 */,
+           "Expected buf to be unchanged or empty, got %s\n",
+           wine_dbgstr_w(buf));
         ok(size == sizeof(about_blank_url)/sizeof(WCHAR) ||
            size == sizeof(buf)/sizeof(buf[0]), /* IE8 */
            "size=%d\n", size);