Make the 'subfeature_earlier_implementation' lint stricter (#6558)
Make the 'subfeature_earlier_implementation' lint stricter (#6558)

Previously it wouldn't compare versions if either was a ranged value
starting with '≤'. However, '≤18' is definitely earlier than '79', to
take Edge numbers as an example, so the comparison can be made in one
direction.

There are no violations of this tighter check.
mdn/browser-compat-data,mdn/browser-compat-data,chrisdavidmills/browser-compat-data,chrisdavidmills/browser-compat-data