This patch: - changes `let` into `const` throughout codebase - adds eslint check to prefer const over let
This patch: - fixes multimap implementation to work properly in node - moves ESTreeWalker from third-party into utils/doclint. ESTreeWalker license is compliant with Apache2.0.
This patch introduces new interception API, via killing InterceptedRequest and giving the `abort` and `continue` methods to the Request object.
