[perl #67700] Method calls after blocks passed to list-operator methods are parsed incorrectly

[Tobias Leich via RT]

Design docs got aligned to rakudo so that method calls on blocks just do what 
one would expect.

Patch: https://github.com/perl6/specs/commit/d1d502fb71
Tests: https://github.com/perl6/roast/commit/95a28225ed

Closing ticket.