Submit PR to parser gem to expose last line number on Parser::Source::Buffer

[floehopper]

From Further Work section of blog post:

At the moment the code delves rather too deeply into the innards of the parser gem i.e. it calls Parser::Source::Buffer#decompose_position to determine the last line number of the method definition. It would probably be better to submit a patch to the parser gem to make the last line available directly on Parser::Source::Buffer.