We anyway use only one property named "inspector-state"(see WebDevToolsAgentImpl.cpp).
Created attachment 109617 [details] Patch
Committed r96590: <http://trac.webkit.org/changeset/96590>
This was only first step. Next step is to remove obsolete methods.
Created attachment 109625 [details] Patch
Committed r96682: <http://trac.webkit.org/changeset/96682>