[Webkit-unassigned] [Bug 121876] New: Starting at r154614, setting the document scroll position isn't symmetric; can successfully set document.body.scrollTop, but can only read from document.documentElement.scrollTop

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=121876

           Summary: Starting at r154614, setting the document scroll
                    position isn't symmetric; can successfully set
                    document.body.scrollTop, but can only read from
                    document.documentElement.scrollTop
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Unspecified
        OS/Version: Unspecified
            Status: UNCONFIRMED
          Severity: Normal
          Priority: P2
         Component: New Bugs
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: rmondello at apple.com
                CC: darin at apple.com, bdakin at apple.com, gur.trio at gmail.com


Using a WebKit nighty or a ToT build, load a page whose height is sufficient for playing around with scrollTop in Web Inspector, like http://www.w3.org/html/wg/drafts/html/master/

After r154614, `document.body.scrollTop = 400;` will scroll the document, but turning around to read from `document.body.scrollTop` always returns 0. Reading `document.documentElement.scrollTop` gives the document's actual scroll offset at any given time, but setting it with `document.documentElement.scrollTop = 800;`does nothing.

This asymmetry doesn't seem right. Whether it's document.body.scrollTop or document.documentElement.scrollTop which actually sets and gets the document's scrollTop, it should be symmetric.


For reference:
IE10 can read/write document.documentElement.scrollTop
Firefox 23.0.1 can read/write document.documentElement.scrollTop

Chrome (27.0.1453.93) can read/write document.body.scrollTop
Safari (6.0.5) can read/write document.body.scrollTop

WebKit ToT (after r154614):
document.body.scrollTop = 400; // works
document.body.scrollTop; // always returns 0
document.documentElement.scrollTop; // works for reading the value
document.documentElement.scrollTop = 500; // doesn't do anything

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