Update dev dependencies (#3401)

- Everything still works as expected.
  - Remove bundlesize
    - It still uses libtorb which is deprecated and broken on Win and
      requires a full suite of build tools on Mac. Keeping it in the
      package makes it difficult for anyone filing issues to run tests.
    - See: #3396
  - Update grunt and it's plugins
  - Update karma to v4...so much faster!
    - Changed the karma config. Better changes: #3394
  - Update Webpack
    - Uses terser over uglify
  - Update eslint
    - Caused an error in util.js from the `global` directive so the
      directive is removed (it was not needed).
  - Update typescript
    - The old version of tsc didn't know about new features in
      @types/node (like `asserts value`).

Co-authored-by: Jay <jasonsaayman@gmail.com>

lib/utils.js

@@ -2,8 +2,6 @@
 
 var bind = require('./helpers/bind');
 
-/*global toString:true*/
-
 // utils is a library of generic helper functions non-specific to axios
 
 var toString = Object.prototype.toString;