- Sets `https://www.mixcloud.com` as a `requires_iframe_origins` to allow the iframe content to be displayed
- Attempts to render something approximating the Mixcloud content in the preview pane of the Composer, rather than just displaying a large version of the artwork associated with the link
This commit introduces a new site setting: `block_hotlinked_media`. When enabled, all attempts to hotlink media (images, videos, and audio) will fail, and be replaced with a linked placeholder. Exceptions to the rule can be added via `block_hotlinked_media_exceptions`.
`download_remote_image_to_local` can be used alongside this feature. In that case, hotlinked images will be blocked immediately when the post is created, but will then be replaced with the downloaded version a few seconds later.
This implementation is purely server-side, and does not impact the composer preview.
Technically, there are two stages to this feature:
1. `PrettyText.sanitize_hotlinked_media` is called during `PrettyText.cook`, and whenever new images are introduced by Onebox. It will iterate over all src/srcset attributes in the post HTML and check if they're allowed. If not, the attributes will be removed and replaced with a `data-blocked-hotlinked-src(set)` attribute
2. In the `CookedPostProcessor`, we iterate over all `data-blocked-hotlinked-src(set)` attributes and check whether we have a downloaded version of the media. If yes, we update the src to use the downloaded version. If not, the entire media element is replaced with a placeholder. The placeholder is labelled 'external media', and is a link to the offsite media.
If the select-kit header is not in the viewport (scrolled out of view), popper adds a data-popper-reference-hidden attribute.
This PR adds the recommended styles to "hide" the select-kit body when that happens. See
https://popper.js.org/docs/v2/modifiers/hide/
The composer is displayed over the bottom part of the page. To make sure
that no content is covered by the composer, a bottom padding is added
equal to the height of the composer. When the composer is opened or
closed that padding is added after around 300ms because of a debounce.
This commit makes sure that the padding is added as soon as the composer
state changes by using a CSS custom property (variable) and transition
property for a smooth user interface.
Note this commit also introduce a new {{d-popover}} component, example usage:
```hbs
{{#d-popover |state|}}
{{d-button label="foo.things" class="d-popover-trigger"}}
<div class="d-popover-content">
Some content
<div>
{{/d-popover}}
```
- Ensure the set of rendered `<link rel=stylesheet>` tags is consistent
- Add var() references for all crawler-view styles. Basic color definitions are defined first, as a fallback for super old browsers
