Use only babel-eslint to parse

[simonedavico]

Update tests to check for babel-eslint error messages. I was forced to comment out the duplicate identifier test, because babel does not throw errors for duplicate identifiers (see this issue).

Fixes #1100 #1141

Would this be a viable approach? I initially wanted to add a config flag to allow switching between espree and babel-eslint, but it would complicate some cases (e.g., Flow files cannot be parsed by espree).

[vilchik-elena]

@simonedavico thanks for PR! it's all ok from the implementation point of view, but I'm not yet sure that's the way we want to go for parsing.
We will consider it more carefully next time we will have a sprint for SonarJS (hopefully in Feb).

[simonedavico]

Sure, I just needed a fix for our internal infrastructure since we are using stage-0 features, and I thought that while I was at it I could contribute back. Hope you will take into consideration my observations on issue #1100 when you decide how much JS ecosystem you want to support :) thanks!

[slikts]

I'd like to try running this patched version of SonarJS, but not sure how to proceed after building the .jar files; what would be the way to run the patched version with sonar-scanner?

[simonedavico]

@slikts you can find the docs for manually installing plugins here.

[vilchik-elena]

Fixed in #1183