performance problem with comments and locations

[alexander-akait]

Shorty - acorn has bad performance when you have minified file and the locations option enabled.

Original problem - webpack/webpack#14922.
Reproducible example - https://github.com/ling1726/webpack-minified-slow

Steps:

• npm i
• npm run start:slow

In example we don't use acorn directly, but it shows the problem well.

The problem happens here https://github.com/acornjs/acorn/blob/master/acorn/src/tokenize.js#L105, because file is big and it is only one line RegExp is very slow.