test: accomodate multi-global tests in WPT{Runner,TestSpec,Report}

Signed-off-by: Filip Skokan <panva.ip@gmail.com>
Co-authored-by: Aviv Keller <me@aviv.sh>
Signed-off-by: Aviv Keller <me@aviv.sh>
PR-URL: #64894
Fixes: #43583
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matthew Aitken <maitken033380023@gmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>

Author: panva