With the change in r158976, the canAttach method takes into account the level of inspector that is being started, to avoid starting an inspector instance that is inspecting an inspector on the same window. The first level of inspectors is 1, but canAttach checks for m_level > 0, so we are never able to attach.
Created attachment 216572 [details]
*** Bug 124155 has been marked as a duplicate of this bug. ***
Sorry about that. Having the level set to 1 was a last minute change that I've done when the debug build asserted in the HashMap.
Comment on attachment 216572 [details]
Clearing flags on attachment: 216572
Committed r159090: <http://trac.webkit.org/changeset/159090>
All reviewed patches have been landed. Closing bug.