Reviewed by Oliver.

    Reviewed by Oliver.

        <rdar://problem/5106788>
        WebKit loads user style sheets too late as seen in Mail (breaks DataDetectors; Mail flashes wrong font)

        Let the document know when the user style sheet is loading so that it try not to display anything
        until the user style sheet has finished loading.

        * page/Frame.cpp:
        (WebCore::UserStyleSheetLoader::UserStyleSheetLoader):
        (WebCore::UserStyleSheetLoader::~UserStyleSheetLoader):
        (WebCore::UserStyleSheetLoader::setCSSStyleSheet):
        (WebCore::Frame::setUserStyleSheetLocation):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@24025 268f45cc-cd09-0410-ab3c-d52691b4dbfc