Enhance view-markdown-source with line actions

[yakov116]

1. LINKED ISSUES:
   Closes Enhance view-markdown-source with line actions #2542

2. TEST URLS:
   https://github.com/sindresorhus/refined-github/blob/3d517d6cd00e83a51973808c7ff03cae2b692d2b/contributing.md#L7

3. SCREENSHOT:
   

[fregante]

Other than that, LGTM, merge at will.

[yakov116]

@fregante great job! (It's all your code 😀)

[fregante]

I'd like to blame my code because this is a bad idea. Don't we already have access to this code via the page we're loading?

Currently all unrelated code is being stripped by the second parameter of

const dom = await fetchDom(path, '.blob-wrapper');

but I think that we can avoid having to maintain these 70 lines by using something like:

const page = await fetchDom(path);
lineActions /*global*/ = select('blah blah', page);
const source = select('.blob-wrapper', page);

I don't think we even need to customize anything in lineActions since it comes straight from GitHub

[yakov116]

I can give it a shot. This should be part of November lint 🙄

[yakov116]

Don't we already have access to this code via the page we're loading?

Did some debugging. We dont, it looks like its loaded loader on

[fregante]

Indeed. We fetch the blame page but only the regular source page is supposed to have it, like https://github.com/sindresorhus/refined-github/blob/master/.editorconfig#L3

I've noticed this problem because this feature is currently the longest file and to be fair it's a nightmare just looking at it imagining what class will be dropped next by GitHub.

I wonder if we could just fetch it from a random file:

const lineActions = onetime(() => {
	const bar = fetchDom('https://github.com/sindresorhus/refined-github/blob/b1229bbaeb8cf071f0711bc2ed1b40dd96cd7a05/.editorconfig', 'BlobToolbar');
	select('#js-view-git-blame', bar)!.href = new GitHubURL(location.href).assign({route: 'blame'}).href;
	select('#js-new-issue', bar)!.href = `/${getRepoURL()}/issues/new`;
	return bar;
});

We'd need a !isEnterprise but the maintainability improvement is worth it.