`SiteSerializer#is_readonly` is cached for an anonymous user so we have
to clear the cache when disabling readonly mode. Otherwise, the site may
appear to be in readonly mode for an extended period of time.
A per process cache is hard to reason about. During PostgreSQL
failovers. The site may bounce in and out of readonly mode depending on
which server and process that a request hits.
This would prevent failure with connectors templates defining actions as closures. In this case action existence is checked at compile time and not runtime.
When a quote is not expanded and it contains lightboxes, those lightboxes are not displayed and instead we show a link that looks like this `[image_title]`
These still have the lightbox CSS class and so they still get the backgrounds we add to lightboxes while they load. Increasing the selector specificity prevents that from happening.
Historically due to https://meta.discourse.org/t/why-is-discourse-so-slow-on-android/8823
we decreased page sizes of both home page and topic page on android by half.
This was done on the server side and as a side effect and caused page sizes on android
to mismatch between Android and non Android.
Unfortunately about a year ago googlebot started pretending it is Android,
this cause Google to start indexing pages as what android would see. So
it saw double the amount of pages in the index as what exists on desktop.
This in turn caused double the amount of indexing work and a large amount
of broken links on long topics.
This fix removes all special behavior which is no longer needed due to
other performance work in Discourse including raw handlebars on home page
and virtual dom on topic pages.
I tested we do not need this on Blu Advance 5.0 it has 1.3 GHZ mediatec mt6580
This phone retails for around $50 USD.
If we decide long term that we want any hacks like this we will shift them
to the client side. It can just hold data in memory without rendering.
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
