refactor: Ensure type none is properly inverts outcome (#970)
refactor: Ensure type none is properly inverts outcome (#970)

* fix(utils/aggregateChecks.js): replace arithmetic with explicit swapping of outcomes.

* docs(utils/aggregateChecks.js): add comment on why outcomes must be swapped.

dequelabs/axe-core,dequelabs/axe-core,dequelabs/axe-core,dequelabs/axe-core