MDL-75012 js: Drop support for modules built pre-babel
We now include more polyfills than we have ever done, and some of these
cause false-positives on our code to address modules which do not have a
name.
We started adding module names to modules in Moodle 3.8 at _build_ time
and kept support for modules which were not transpiled using Babel
before that point.
We no longer need to support this as all pre-3.8 Moodle versions are
long out of support. The most recent to go out of support was Moodle
3.5, which went completely out of support in May 2021.
We should not support code written and minified without a transpilation
phase from this time any longer.