Chore: Use arrow functions where possible (lexical `this`).

[originalfoo]

• Version: 6.2.1
• Platform:
• Subsystem: various

Following on from #7295, I've spotted similar pattern in many other files:

var self = this;
something(someFunc(...) {
  self.whatever();
});

In most scenarios, this pattern can be replaced with an arrow function, allowing removal of 'self' var:

something((...) => {
  this.whatever();
});

I'd like to use this issue ticket as a hub for several commits/PRs relating to this (one changed file per PR, although there may be several commits in the PR - one for each arrow function implemented in the file).

[addaleax]

although there may be several commits in the PR - one for each arrow function implemented in the file

It’s up to the one who creates the PR how they do it, but the commits will very likely be squashed together anyway.

[originalfoo]

@addaleax it's more so I can interactive rebase or cherry-pick should a specific commit need removing etc; just sort of a habit I got in to.

[addaleax]

@aubergine10 As said, it’s up to you. :)

Tbqh, I’d like to hear or work out some kind of rule of thumb of which types of style-only changes are generally considered worthwhile. These kind of changes tend to generate a lot of noise, and while I see that something like #7378 can improve readability noticeably, I’m not sure that’s always the case.