[Webkit-unassigned] [Bug 100507] New: Progress bar shadow tree sometimes is not relayouted.

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=100507

           Summary: Progress bar shadow tree sometimes is not relayouted.
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: PC
        OS/Version: All
            Status: UNCONFIRMED
          Severity: Normal
          Priority: P2
         Component: Layout and Rendering
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: halyavin at chromium.org


Created an attachment (id=170899)
 --> (https://bugs.webkit.org/attachment.cgi?id=170899&action=review)
test page

Progress bar shadow tree sometimes is not relayouted.
Steps to reproduce:
1. Open page in attachment.
2. Click on a button.
3. See that first bar is updated while second bar is not.

What is going on behind the cover:
HTMLProgressElement has a shadow tree which consist in 3 nested divs. The most nested div (HTMLProgressElement::m_value) represents progress bar value and is updated by HTMLProgressElement::didElementStateChange method.

When javascripts on the page sets the second progress bar value, m_value node loses IsStyleAttributeValidFlag flag. Then <progress> element is inserted into tree and InDocumentFlag is set in m_value. Then Element::recalcStyle is called on HTMLProgressElement and it executes reattach method for it. Method reattach calls attach and as result m_value receives IsAttachedFlag. Then HTMLProgressElement::attach calls didElementStateChange method which calls m_value->setWidthPercentage which sets InlineStyleChange flag to m_value node and ChildNeedsStyleRecalc flag to all its parent nodes. But then reattach methods returns and Element::recalcStyle calls clearNeedsStyleRecalc and clearChildNeedsStyleRecalc methods on HTMLProgressElement node. 

So now we have m_value node that needs style recalculation but HTMLProgressElement node doesn't have ChildNeedsStyleRecalcFlag flag. As a result, any subsequent changes to progress element doesn't do anything since m_value is already marked as needed to recalculate style. But m_value never recalculates style since HTMLProgressElement doesn't have ChildNeedsRecalcFlag.

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