This discussion started on #4983. Please read the discussion there first!

For example:

• Before shipping compat
  • Limits that we discover but don't want to hardcode to 0 at the start
  • Features that we discover and don't want to hard-disallow at the start
• After shipping compat
  • Hardcoded limits that we want to upgrade to configurable limits
  • Hard-disallowed feature functionality that we want to upgrade to configurable features

The problems are:

• Feature detection in compat-able browsers - solved by adapter.limits/features
• Feature detection in compat-less browsers
  • Can we expect of compat-less browsers that they will ship new Core features/limits that were added for the benefit of Compat?