We have a bunch of methods that we traditionally did call during compilation, like WatchpointSet::isStillValid() and Structure::get(). At least for those methods, we should add asserts that check that they are not being called during compilation. In a serial compilation mode, we should set a thread-local to denote start/end of compilation; in a concurrent compilation mode, we should check that we aren't in the compiler thread.
Created attachment 199979 [details] the patch
Comment on attachment 199979 [details] the patch r=me
Landed in http://trac.webkit.org/changeset/149301