Previously, the document was shown as soon as the HTML was received, but before
the embedded components were ready (e.g. downloaded and instantiated). This
caused FOUC (Flash Of Uninstantiated Components).
This commit fixes it by preparing the new document in an off-DOM node and
swapping the nodes when the embedded components are ready.
PR Close#18428
Using `display: none` on the `<h1>` causes `innerText` to not work as expected
and include the icon ligature (`link`) in the title. This caused the window
title on the angular.io Home page to appear as "Angular - link".
This commit fixes it by not generating anchors at all for headings with the
`no-anchor` class.
Fixes#20427
PR Close#20440
The window title is derived based on the current document's `<h1>` heading. Such
headings may contain hidden/non-visible content (e.g. textual name of font
ligatures: `<i class="material-icons">link</i>`) that should not be included in
the title.
This commit fixes this by using `innerText` (instead of `textContent`) to
extract the visible text from the `<h1>` heading. It will still fall back to
`textContent` on browsers that do not support `innerText` (e.g. Firefox 44).
Fixes#17732
`innerText` is not supported in Firefox prior to v45. In most cases (at least
the ones we are interested in), `innerText` and `textContent` work equally well,
but `textContent` is more performant (as it doesn't require a reflow).
From [MDN][1] on the differences of `innerText` vs `textContent`:
> - [...]
> - `innerText` is aware of style and will not return the text of hidden
> elements, whereas `textContent` will.
> - As `innerText` is aware of CSS styling, it will trigger a reflow, whereas
> `textContent` will not.
> - [...]
[1]: https://developer.mozilla.org/en-US/docs/Web/API/Node/textContent#Differences_from_innerTextFixes#17585
