Evaluate targeting more modern runtimes.

Instead of targeting ECMAScript 5.1 we should probably target a more modern runtime, e.g ES2017 / ES2018. This means removing support legacy browsers such as IE11.

SubTasks:

• Chose target runtime (keep ES5 target).
• Change TSC compilation target.
• Inspect if this change has any performance impact. (no meaningful difference)
• Evaluate if bundling flows need to be modified.
• Document as Breaking Change
• Update root README compatibility section documentation.
• remove hacks for old engine around function.name
• Remove flows using isES2015MapSupported -https://github.com/Chevrotain/chevrotain/blob/239c59fd48ea650b21fb31b3f2492fe1aa865b44/packages/utils/src/api.ts#L426-L428
• Evaluate removing hacks around Function.prototype.name
• https://github.com/Chevrotain/chevrotain/blob/24f37409689f7a31bb3290c4e9218a7fa7a34e07/packages/chevrotain/src/lang/lang_extensions.ts#L10-L25

[NaridaL]

Yeah ES2015 seems fine. As far as I’m concerned as long as it runs on the latest Node LTS it’s fine 😅

[bd82]

Changing the TSC target to ES2015 resulted in:

• A slight performance degradation (~3%)
• Some failing tests.
• Breaking examples / benchmark scenarios
  • Because it seems one cannot extend an ES2015 class using prototype inheritance https://stackoverflow.com/questions/30689817/es6-call-class-constructor-without-new-keyword

The one advantage was a ~12% decrease in minified bundle size.

I will keep ES5 compilation target for now. and will only remove the various hacks to support old engines.