Add check in GUI test for file loading failure Since https://github.com/rust-lang/rust/pull/101702, some resources location need to be updated in case their content changed because then their hash will change too. This will prevent errors like https://github.com/rust-lang/rust/pull/104114 to happen again. The second commit is to prevent CORS errors: when a file is linked from a file itself imported, the web browser considers they come from a different domain and therefore triggers the error. The option tells the web browser to ignore this case. cc ```@jsha``` r? ```@notriddle```