[Webkit-unassigned] [Bug 70868] New: Stylesheets not created by the parser should not block scripts

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=70868

           Summary: Stylesheets not created by the parser should not block
                    scripts
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Unspecified
        OS/Version: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Page Loading
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: jnd at chromium.org
                CC: tonyg at chromium.org


Created an attachment (id=112446)
 --> (https://bugs.webkit.org/attachment.cgi?id=112446&action=review)
test file to show how a stylesheet not created by parse blocks script

According to spec(http://dev.w3.org/html5/spec/Overview.html#a-style-sheet-that-is-blocking-scripts),  a style sheet that is blocking scripts if the element was created by that Document's parser. So Stylesheets not created by the parser should not block scripts, which means that that script shouldn't be dependent on style being recalculated.

By currently in WebKit, Stylesheets not created by the parser did block scripts.
The attached test file shows how it happens. (http://en.wikipedia.org/wiki/United_States_of_America is a case in real world).
>From the attached devtool timeline snapshot, you can see the stylesheets not created by the parser triggered multiple immediate style recalculations, which block script for long time.

I will send a patch to fix it

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