https://bugs.webkit.org/show_bug.cgi?id=47615
<rdar://problem/9001214>
        
Reviewed by Darin Adler.

This is a resubmission of a patch that was landed a while ago then rolled
back because of a build failure on SnowLeopard and Leopard on the 32-bit builds.

This patch adds a way for WebKit2 to create NSAttributedStrings from
a DOM range without using the AppKit api initWithDOMRange that internally
needs to access the WebView. The NSAttributedString is needed to create
RTF formats in the pasteboard.
This is to be considered a first step, since in the future we want to have
an implementation based on the TextIterator.
* WebCore.xcodeproj/project.pbxproj:
* platform/mac/HTMLConverter.h: Added.
* platform/mac/HTMLConverter.mm: Added.
* platform/mac/PasteboardMac.mm:
(WebCore::Pasteboard::writeSelection):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@80615 268f45cc-cd09-0410-ab3c-d52691b4dbfc