Refactoring: Move m_mayDisplaySeamlesslyWithParent down to Document

The member is used only in Document, thus no reason to
stay in SecurityContext.

TEST=none
BUG=none
R=haraken@chromium.org, abarth, haraken, hayato

Review URL: https://codereview.chromium.org/27615003

git-svn-id: svn://svn.chromium.org/blink/trunk@159829 bbb929c8-8fbe-4397-9dbb-9b2b20218538
String Document::suggestedMIMEType() const
{
    if (isXHTMLDocument())
        return "application/xhtml+xml";
    if (isSVGDocument())
        return "image/svg+xml";
    if (xmlStandalone())
        return "text/xml";
    if (isHTMLDocument())
        return "text/html";

    if (DocumentLoader* documentLoader = loader())
        return documentLoader->responseMIMEType();
    return String();
}

String Document::suggestedMIMEType() const
{
    if (isXHTMLDocument())
        return "application/xhtml+xml";
    if (isSVGDocument())
        return "image/svg+xml";
    if (xmlStandalone())
        return "text/xml";
    if (isHTMLDocument())
        return "text/html";

    if (DocumentLoader* documentLoader = loader())
        return documentLoader->responseMIMEType();
    return String();
}
