Follow-up to Idae6755c90eacaab1a9daa88c6e28850d427810c. These styles
still used #content instead of the new way of specifying the target
container.
Extra cleanup:
* Don't apply custom styles to #firstHeading when it's outside of
the target container
* Remove unnecessary rule (it was added in 6d8fbd8221 to support
an absolutely-positioned loading toolbar, but it is no longer
positioned that way)
Bug: T310839
Depends-On: Idb2a743c93316786d6d36e1989cf6620a6092281
Change-Id: Ib5e8f98eacf763e360fae79337d3f2733b1a101b
* Append the toolbar before starting the scroll
* If the toolbar is floating set the anchor to full height
immediately. This shouldn't cause the content to jump down
due to scroll anchoring:
(https://developer.mozilla.org/en-US/docs/Web/CSS/overflow-anchor/Guide_to_scroll_anchoring)
But add our own logic for it for browsers which don't support that.
* Now the browser only has to deal with the scroll animation,
and not the height animation of the toolbar anchor at the
same time, making it smoother and less buggy.
Bug: T301773
Change-Id: I61d533d40758d559b03c858e0006ef2e4f0fcd16
This doesn't change the position of the loading bar, but it keeps it
still if any scrolling happens. Previously we expected the user probably
wouldn't scroll while VE is loading, but in subsequent commits we
will trigger automatic scrolling in section editing mode.
Change-Id: I1404ccd77583d808ef79291c6cb4f561e76bd41c
