My best advice is wait, your using unstable and this is not to uncommon with AMD64, it means the package for the kdewebdev module has been updated, but a library hasn't ( 64 libraries can sometimes take a little extra time. ).
Install the packages kde-amusements, kde-core, kdeaccessibility, kdeaddons, kdeadmin, kdeartwork, kdegraphics, kdemultimedia, kdenetwork, kdepim and kdeutils. You'll have a complete kde system apart from Quanta, Kommander, KFileReplace, KImageMapEditor, KLinkStatus and kxsldbg.
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