Keyword index of first keyword encountered in parameter lists is problematic because other variables during parsing can still be encountered (see #8577 for an example).

This fix is a shorter-term fix where we maintain a bitlist to indicate which parameters are keywords. This removes the need for all keywords to be definedcd at the end of the scope.

The longer term fix is to fully describe the parameters which can be introspected by the callsite. This goes way beyond this fix as it outlines how we can easily map known keyword values to keyword parameters in the method and eliminate storing the keywords in a hash (in this case we can pass them as positional parameters). This is a larger work item and is too much for us in the short term.