Fixes <http://webkit.org/b/29181> User script/stylesheet tests are
skipped on Windows

Reviewed by John Sullivan.

WebKit/win:

* Interfaces/IWebViewPrivate.idl: Added addUserScriptToGroup,
addUserStyleSheetToGroup, removeUserContentFromGroup,
removeAllUserContentFromGropu to match the Mac SPI.

* WebView.cpp:
(WebView::addUserScriptToGroup):
(WebView::addUserStyleSheetToGroup):
(WebView::removeUserContentFromGroup):
(WebView::removeAllUserContentFromGroup):
* WebView.h:
Added. Implementation was based on similar methods in WebView.mm.

WebKitTools:

* DumpRenderTree/win/DumpRenderTree.vcproj: Link all configurations
against comsuppw.lib so we can use _bstr_t.

* DumpRenderTree/win/LayoutTestControllerWin.cpp: Fixed #include
order, added #include of comutil.h for _bstr_t.

(bstrT): Helper function to convert a JSStringRef to a _bstr_t.
(LayoutTestController::addUserScript):
(LayoutTestController::addUserStyleSheet):
Implemented. Implementations were based on those in
LayoutTestControllerMac.mm.

LayoutTests:

* platform/win/Skipped: Removed the userscripts directory.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@48302 268f45cc-cd09-0410-ab3c-d52691b4dbfc