EndPrinting message should be sent synchronously when printing was initiated...

    EndPrinting message should be sent synchronously when printing was initiated from DOM.
        https://bugs.webkit.org/show_bug.cgi?id=84049
        <rdar://problem/11096575>

        Reviewed by Oliver Hunt.

        * UIProcess/WebPageProxy.cpp: (WebKit::WebPageProxy::printFrame): When printing is
        initiated by WebProcess, all messages from UI process are sent synchronously to
        avoid being queued, and so should EndPrinting.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@114286 268f45cc-cd09-0410-ab3c-d52691b4dbfc