`webext.js` module needs to be explicitly imported. Added time-based heuristic to decide when a webpage loses communication with background process.
Allow arbitrary indent inside literal array declaration.
Support no-indentation for file-level if block or arrow function block.
Eslint supports newer JS syntax such as static fields in classes, which is supported by all browsers/version with official uBO support. Reference: https://eslint.org/docs/latest/ Fixing all warnings for all JS files will be done over time.
