This feature is used for defer loading of images and in future for post cloaking
This gives us a polyfill so we can safely use the feature in problem browsers
The polyfill supports "polling" but it does not appear we need it yet.
If we discover anything odd here, consider setting poll interval per:
https://github.com/w3c/IntersectionObserver/tree/master/polyfill
```
var io = new IntersectionObserver(callback);
io.POLL_INTERVAL = 100; // Time in milliseconds.
```
Keeping the mutation observer cause we often mutate the DOM
* Add missing icons to set
* Revert FA5 revert
This reverts commit 42572ff
* use new SVG syntax in locales
* Noscript page changes (remove login button, center "powered by" footer text)
* Cast wider net for SVG icons in settings
- include any _icon setting for SVG registry (offers better support for plugin settings)
- let themes store multiple pipe-delimited icons in a setting
- also replaces broken onebox image icon with SVG reference in cooked post processor
* interpolate icons in locales
* Fix composer whisper icon alignment
* Add support for stacked icons
* SECURITY: enforce hostname to match discourse hostname
This ensures that the hostname rails uses for various helpers always matches
the Discourse hostname
* load SVG sprite with pre-initializers
* FIX: enable caching on SVG sprites
* PERF: use JSONP for SVG sprites so they are served from CDN
This avoids needing to deal with CORS for loading of the SVG
Note, added the svg- prefix to the filename so we can quickly tell in
dev tools what the file is
* Add missing SVG sprite JSONP script to CSP
* Upgrade to FA 5.5.0
* Add support for all FA4.7 icons
- adds complete frontend and backend for renamed FA4.7 icons
- improves performance of SvgSprite.bundle and SvgSprite.all_icons
* Fix group avatar flair preview
- adds an endpoint at /svg-sprites/search/:keyword
- adds frontend ajax call that pulls icon in avatar flair preview even when it is not in subset
* Remove FA 4.7 font files
* First take on subsetting svg icons
* FontAwesome 5 svg subset WIP
* Include icons from plugins/badges into svg sprite subset
* add svg icon support to themes
* Add spec for SvgSprite
* Misc. SVG icon fixes
* Use FA5 svgs in local-dates plugin
* CSS adjustments, fix SVG icons in group flair
* Use SVG icons in poll plugin
* Add SVG icons to /wizard
Run `prettier --write "app/assets/stylesheets/**/*.scss" "plugins/**/*.scss"` after making sure you installed it with `yarn`
It's recommended to configure your editor to run prettier on file save.
