For some reason when doing a debug build, the static libraries aren't referenced by their correct names on Windows (JavaScriptCored.lib vs JavaScriptCore, for example) when building the dll. Symptoms are errors such as: NMAKE : fatal error U1073: don't know how to make 'c:\Users\Joel\dev\qt5\qtwebkit\WebKitBuild\Debug\Source\WebCore\release\WebCore.lib' I presume the solution is $$qtLibraryTarget() inserted at a suitable place, but I do not know where that place is.
Created attachment 147339 [details] Patch
I recall seeing this patch on your screen :).
Committed r120685: <http://trac.webkit.org/changeset/120685>