Remove unnecessary doctype setup in spec
Fix the bug that _register-load-callbacks receives empty doc.
Test if the renderer wait for CSS and images
Reduce duplication of CSS test files
Remove delay function.
Add delay when updating CSS for pseudo element styles, but it seems not working
Remove @import in test css because its loading is not stable / consistent across test trials.
Set unimplemented tests to pending
Implementing pseudo-element test, but the test fails for no reason
Skip pseudo element test for now…