1415819 - (deadcode-codecoverage) [meta] Delete dead code using the files with zero coverage report

Status: NEW

(Testing :: Code Coverage, enhancement)

Description

[Marco Castelluccio [:marco]]

The files with zero coverage report (https://marco-c.github.io/code-coverage-reports/) can give an idea of files that might be dead code.

We can't simply remove all of them, since some might simply be untested, but many of the completely untested files are indeed dead code.

Removing these files has several benefits:
1) Reduce build times;
2) Reduce the size of the resulting binary;
3) Reduce attack surface, if the files contain code that might be executable in some corner case that we don't actively support anymore (e.g. bug 1413854).