The initial implementation had a bug where a class declaration
"statement" would be seen as covering all the lines of all the methods
in that class. This change fixes that case, so that the lines of
methods and inner statements are not "part" of their outer containers.
This generates a more detailed JSON coverage file containing maps of
exactly what statements were executed by tests. This also extracts
the data from this file and updates the PR with a comment showing how
much of the changed code is covered by tests.
Joey Parrish