Fix <rdar://5133816> keepWebHistory is not implemented

 Fix <rdar://5133816> keepWebHistory is not implemented

 WebCore:

         Add wrappers around CoCreateInstance to COMPtr

         I followed the example of the Query constructor and query method by
         adding a Create constructor and create method.

         Reviewed by Darin.

         * platform/win/COMPtr.h:
         (COMPtr::COMPtr): Added a new constructor that calls
         CoCreateInstance.
         (COMPtr::create): Added.
         (COMPtr::createInstance): Added.

 WebKitTools:

         Fix <rdar://5133816> keepWebHistory is not implemented

         Fixes fast/history/clicked-link-is-visited.html.

         Reviewed by Darin.

         * DumpRenderTree/win/DumpRenderTree.cpp:
         (runTest): Clear the optionalSharedHistory.
         * DumpRenderTree/win/LayoutTestControllerWin.cpp:
         (LayoutTestController::keepWebHistory): Set the optionalSharedHistory.

 LayoutTests:

         Remove a now-passing test from the Windows Skipped file

         Reviewed by Darin.

         * platform/win/Skipped:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@27691 268f45cc-cd09-0410-ab3c-d52691b4dbfc