Remove custom file watcher
Remove custom file watcher

It seems as though the file watcher is being excesively
reinitialized, whereby only certain files end up being watched.

The Chokidar watcher may yet be the best solution, but for now it
will be removed while the core preprocessor is refactored.

jlmakes/karma-rollup-preprocessor,jlmakes/karma-rollup-preprocessor,showpad/karma-rollup-preprocessor