Installa Safari, and then copy all files under "C:\Program Files\Common Files\Apple\Apple Application Support" to binary directory of WebKit project, such as "D:\WebKit\WebKitBuild\Debug\bin"
To verify the browser you built works, just to click "WinLauncher.exe" to see if a new browser is launched and a new url can be loaded (the url must contains schema, such as http://)
Click D:\WebKit\Source\WebKit\win\WebKit.vcproj\WebKit.sln to open WebKit project, the project entry is "WinLauncher::_tWinMain", then you can debug WebKit step by step.
Issue
Issue: WebCore.lib(CSSParser.obj) : error LNK2019: unresolved external symbol "public: int __thiscall WebCore::CSSParser::lex(void)" (?lex@CSSParser@WebCore@@QAEHXZ) referenced in function "public: int __thiscall WebCore::CSSParser::lex(void *)" (?lex@CSSParser@WebCore@@QAEHPAX@Z) 8>D:\WebKit\out\Debug\bin\WebKit.dll : fatal error LNK1120: 1 unresolved externals