[webkit-dev] CSSOM View behavior for scrollLeft, scrollTop, scrollWidth etc

[Frédéric Wang]

Hi everybody,

I'd like to announce that I started to implement the behavior for
scrollLeft, scrollTop, scrollWidth, scrollHeight, scrollTo, scrollBy and
scrollingElement [1] as specified by the CSSOM View specification [2].

To summarize, the main difference is which element to use in order to
set or get the scroll properties of the viewport in standard
(non-Quirks) mode:

* The CSSOM View spec says it should be document.documentElement and
most browsers implement it that way.
* Chromium used to use document.body but this has recently been changed
to follow the CSSOM View spec [3].
* WebKit still uses document.body and I'm proposing to change this behavior.

Note that this is likely to break existing content. The change was
attempted in WebKit in the past but broke some non-regression tests [4].
Chromium people also had some issues when trying to ship the change but
things went well at the end [5].

For now I'm developing it under a CSSOMViewScrollingAPI developer flag.
I was able to run the tests with that flag enabled, modulo a few test
adjustments.

[1] https://bugs.webkit.org/show_bug.cgi?id=5991
[2] https://drafts.csswg.org/cssom-view
[3]
https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/X64Sg16RhT4
[4] https://bugs.webkit.org/show_bug.cgi?id=106133,
https://bugs.webkit.org/show_bug.cgi?id=121876
[5]
https://groups.google.com/a/chromium.org/forum/#!msg/blink-dev/2iOz5-fgD8Y/GO7qLkg4BwAJ
; https://bugs.webkit.org/show_bug.cgi?id=5991#c20

-- 
Frédéric Wang - frederic-wang.fr