Comment by bluGill

LGPL yes. However the rest is false. GPL would have made a bit more of their fork open source, but Apple would have otherwise had no problem forking it and not allowing contributors. KHTML developers often complained in those early years that their fork was in theory open source, but it quickly became so different that it wasn't possible to figure out which changes were wroth porting and which not.

I suspect a lawyer could look at the state of WebKit and Chrome these days and conclude there is so little original code remaining that it can be re-licensed to closed source (see a lawyer for what this complex bit of law means) - worst case they only have to rewrite a small amount.