Reviewed by Darin.

        - test for http://bugs.webkit.org/show_bug.cgi?id=12973
          REGRESSION: Reproducible assert while loading this test file if css is already in the cache

        * fast/dom/css-cached-import-rule-expected.checksum: Added.
        * fast/dom/css-cached-import-rule-expected.png: Added.
        * fast/dom/css-cached-import-rule-expected.txt: Added.
        * fast/dom/css-cached-import-rule.html: Added.

WebCore:

        Reviewed by Darin.

        - fix http://bugs.webkit.org/show_bug.cgi?id=12973
          REGRESSION: Reproducible assert while loading this test file if css is already in the cache

        Test: fast/dom/css-cached-import-rule.html

        Replaced some direct calls to document->stylesheetLoaded() with calls to
        the sheet's checkLoaded(). The latter calls back to the element's sheetLoaded() --
        which notifies the document of the load -- and then updates the sheet's
        loadCompleted() flag, ensuring that it stays in sync with whether the stylesheet
        is still considered pending by the document.

        * dom/ProcessingInstruction.cpp:
        (WebCore::ProcessingInstruction::parseStyleSheet):
        * dom/StyleElement.cpp:
        (WebCore::StyleElement::childrenChanged):
        * html/HTMLLinkElement.cpp:
        (WebCore::HTMLLinkElement::process):
        (WebCore::HTMLLinkElement::setCSSStyleSheet):
        * ksvg2/svg/SVGStyleElement.cpp:
        (WebCore::SVGStyleElement::sheetLoaded):
        * ksvg2/svg/SVGStyleElement.h:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@20098 268f45cc-cd09-0410-ab3c-d52691b4dbfc