As Composer is now widely used in the PHP world, having to run composer
install before running the test suite is expected. This also has the
nice benefit of removing a bunch of code, making things easier to
maintain (there is only one place to declare a dev dependency), and
probably more.
Use the same format as object methods to describe closures and collect
the file and the line where it's been declared.
These informations should be added in the views of the webprofiler.
