Error recovery

[KFlash]

It's on my TODO to add error recovery to Meriyah from v. 2.0. The code is still experimental, and not usable yet. And it can only recover from lexer.

This is somehow similar to what Babel does in this PR babel/babel#10363 , but with Meriyah I plan to add both recovery and incremental parsing, so it can recover from all errors.

The bad news with this is that I may refactor the entire Meriyah code base to archive this goals, so the code is kept private until it's completed and ready to be pushed.

The good news is that the locale code performs 10 - 15% faster than current Meriyah.

For now I have a lot to fix in my RL, but it will be implemented one day.

cc / @aladdin-add @nchanged

[KFlash]

RL take all my time now, but latest recovery code I was working on can be found in the recovery branch. The lexer is almost done, and the parser doesn't die on invalid syntax, but require a lot of work :)

Example:

parseScript(`function( {}`, {
        onError: function(err: string) {
          console.log(err)  // 'Expected ) '
        }
      });

Outputs:

{ type: 'Program', sourceType: 'script', body: [ undefined ] }

cc / @aladdin-add Thoughts?

[KFlash]

Closing as this will land in 2.0.