Some times connection arrive, are given 404 responses, then disconnect,
resulting in ECONNRESET errors on the socket.  After we began monitoring
UncaughtExceptions, these errors show up. Suppress them with a handler
that ignores errors.

This results in a significant dependencies reduction. New version of
chokidar also promises significant memory and performance improvements.

* chore: remove unused devDependencies

* chore: update some devDependencies

* fix(test): fixed flaky reconnecting test

cc2eff2 introduced different behavior depending on whether socket reconnected or browser reconnected after reload. This lead to the reconnecting test being flaky as, depending on the timing, it will trigger second test run and result in unexpected output.

* fix(test): remove broken monitor action for Cucumber

The issue is that it resulted in the following sequence of actions:
- run karma start
- run karma run
- and then instantly kill karma start command

This resulted in flaky tests because the kill could race, resulting in
incomplete output. In fact test was unnecessary complicated as it was
enough to use runOut, which asserts output of the karma run command.

* fix(test): guard from repeated executions of the karma run

'data' event handler may be called multiple times, which will result in
multiple calls to karma run. To take it even further, its execution is
delayed by setTimeout, which means that subsequent executions will run
while next test scenario is in progress and may mess it up. To prevent
this make sure that karma run is executed only once independently of how
many time 'data' event is fired.

Mocha 5+ dropped support for IE 8 and IE 9. This leads to failing
BrowserStack tests, so reverting back to version 4 until Karma decides
to drop support for the mentioned browsers.

…3316)

Columns in original stack are 1-based, but
SourceMapConsumer.prototype.originalPositionFor(generatedPosition)
accepts 0-based column and returns 0-based column too.
This change converts columns from 1-based to 0-based forth and back.

Closes #3324

While flatten is accruate and works with circular data, it's too hard to read.