Remove long gone WebExtensions features

[Elchi3]

Description

We consider features irrelevant once they are removed from all browsers for more than two years. This is the case with a few WebExtensions features that this PR proposes to remove from the docs.

Motivation

Cleaning up data and docs, so that readers don't have to read stuff that is not interesting anymore and distracts from other relevant and current information on the page.

Additional details

None.

Related issues and pull requests

BCD companion PR: mdn/browser-compat-data#21305

[github-actions]

Preview URLs

• /en-US/docs/Mozilla/Add-ons/WebExtensions/API/downloads
• /en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/theme

External URLs (1)

URL: /en-US/docs/Mozilla/Add-ons/WebExtensions/API/downloads
Title: downloads

• https://developer.chrome.com/docs/extensions/reference/downloads/ (1 time)

(comment last updated: 2023-12-19 10:58:55)

[rebloor]

@Elchi3 I think we need some further changes:

• the two deleted images are used to illustrate tab_background_text and frame, so should be renamed rather than deleted (see lines 382 and 760)
  - headerURL is mentioned in lines, 145 to 151. Perhaps change the text to "Optional in desktop Firefox 60 onwards. Required in Firefox for Android."
• note referring to textcolor on lines 482 to 485
• remove accentcolor and textcolor from the alias section (from line 1252). We would appear now to only have one alias, for bookmark_text/toolbar_text

[Elchi3]

Thanks @rebloor! Will update this PR. Local preview doesn't really work unfortunately due to mdn/yari#4654

[zfox23]

@Elchi3 poking you regarding updating this PR :) Thank you for your help.

[Elchi3]

@zfox23 Thanks for the poke :) I will try to come back to this. It hard to contribute to this page though given mdn/yari#4654. Do you know a workaround?

[rebloor]

@Elchi3 how are you obtaining your preview? I've just checked mine running from yarn start, which is rendering on port 5042 and doesn't have an issue rendering manifest.json content. Unfortunately, I couldn't explain why this is different from what was happening when I reported mdn/yari#4654.

[Elchi3]

@rebloor Thank you so much!
http://localhost:5042/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/ works and
http://localhost:3000/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/ does not!

I've made the requested changes. Please take another look.

[rebloor]

@Elchi3, Sorry for the delay in reviewing your update. Everything looks good, and I've merged. Thanks for your help.